Micro cilia array and use thereof

ABSTRACT

A micromechanical actuator having the ability to move in two directions. The actuator can be manufactured in planar arrays using semiconductor manufacturing equipment. The planar array of actuators can be used as a microcillia array. The actuators are formed from two layers of electrically resistive material which are used to heat a non-conductive material which has a high coefficient of thermal expansion. The pattern of resistive material in the two layers is arranged such that the actuator can be bent in two directions, both in the plane of the actuator and normal to the plane of the actuator.

FIELD OF THE INVENTION

The present invention relates to a thermal actuator device and, in particular, discloses details of a micro cilia array and use thereof.

The present invention further relates to actuator technology and particularly relates to a micro mechanical actuator having improved characteristics.

BACKGROUND OF THE INVENTION

Thermal actuators are well known. Further, the utilization and construction of thermal actuators in micro mechanics and Micro Electro Mechanical Systems (MEMS) is also known.

Unfortunately, devices constructed to date have had limited operational efficiencies which have restricted the application of thermal actuators in the MEMS area. There is therefore a general need for improved thermal actuators for utilization in the MEMS and other fields and in particular the utilization of multiple actuators in a cilia array.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved form of thermal actuator having a large range of operational capabilities in addition to the formation of large arrays of thermal actuators for the movement of objects in close proximity with the actuators.

In accordance with the first aspect of the present invention, there is provided a thermal actuator comprising an elongate member of heat expansible material adapted to be anchored at a proximal end and having a movable distal end, and a plurality of independently heatable resistive elements incorporated in the elongate member located and arranged such that when selected resistive elements are heated by the application of electric current, the distal end is provided with controlled movement in two mutually orthogonal directions due to controlled bending of said elongate member.

Preferably, said elongate member is substantially rectangular in section having an upper and a lower surface, and wherein three said heatable resistive elements are provided extending in an elongate direction along said member, two of said three elements being located side by side adjacent one of said upper and lower surfaces, and the third of said three elements being located adjacent the other of said upper and lower surfaces, laterally aligned with one of said two elements.

Preferably, said three elements are electrically connected to a common return line at their ends closest to the distal end of said member.

Further the resistive elements are formed from a conductive material having a low coefficient of thermal expansion and an actuation material having a high coefficient of thermal expansion, said resistive elements being configured such that, upon heating, said actuation material is able to expand substantially unhindered by the conductive material.

Preferably, the conductive material undergoes a concertinaing action upon expansion and contraction, and is formed in a serpentine or helical form. Advantageously, the common line comprises a plate like conductive material having a series of spaced apart slots arranged for allowing the desired degree of bending of the conductive material. Further, the actuation material is formed around the conductive material including the slots. The actuator is attached to a lower substrate and the series of resistive elements include two heater elements arranged on a lower portion of the actuation substrate and a single heater and the common line formed upon portion of the action substrate.

Preferably the actuation material comprises substantially polytetrafluoroethylene. One end of the thermal actuation is surface treated so as to increase its coefficient of friction. Further, one end of the thermal actuator comprises only the actuation material.

In accordance with a second aspect of the present invention, there is provided a cilia array of thermal actuators comprising one end that is driven so as to continuously engage a moveable load so as to push it in one direction only. Further, adjacent thermal actuators in the cilia array are grouped into different groups with each group being driven together in a different phase cycle from adjacent groups. Preferably the number of phases is four.

BRIEF DESCRIPTION OF THE DRAWINGS

Notwithstanding any other forms which may fall within the scope of the present invention, preferred forms of the invention will now be described, by way of example only, with reference to the accompanying drawings which:

FIG. 1 is a perspective view of an arrangement of four single thermal actuators constructed in accordance with the preferred embodiment.

FIG. 2 is a close-up perspective view, partly in section, of a single thermal actuator constructed in accordance with the preferred embodiment.

FIG. 3 is a perspective view of a single thermal actuator constructed in accordance with the preferred embodiment, illustrating the thermal actuator being moved up and to a side.

FIG. 4 is an exploded perspective view illustrating the construction of a single thermal actuator in accordance with the preferred embodiment.

DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS

Turning to FIG. 1, there are illustrated 4 MEMS actuators 20, 21, 22, 23 as constructed in accordance with the preferred embodiment. In FIG. 2, there is illustrated a close-up perspective view, partly in section, of a single thermal actuator constructed in accordance with the preferred embodiment. Each actuator, e.g. 20, is based around three corrugated heat elements 11, 12 and 13 which are interconnected 14 to a cooler common current carrying line 16. The two heater elements 11, 12 are formed on a bottom layer of the actuator 20 with the heater element 13 and common line 16 being formed on a top layer of the actuator 20. Each of the elements 11, 12, 13, 14 and 16 can be formed from copper via means of deposition utilising semi-conductor fabrication techniques. The lines 11, 12, 13, 14 and 16 are "encased" inside a polytetrafluoroethylene (PTFE) layer, e.g. 18 which has a high coefficient of thermal expansion. The PTFE layer has a coefficient of thermal expansion which is much greater than that of the corresponding copper layers 12, 13, 14 and 16. The heater elements 11-13 are therefore constructed in a serpentine manner so as to allow the concertinaing of the heater elements upon heating and cooling so as to allow for their expansion substantially with the expansion of the PTFE layer 18. The common line 16, also constructed from copper is provided with a series of slots, e.g. 19 which provide minimal concertinaing but allow the common layer 16 bend upwards and sideways when required.

Returning now to FIG. 1, the actuator, e.g. 20, can be operated in a number of different modes. In a first mode, the bottom two heater elements 11 and 12 (FIG. 2) are activated. This causes the bottom portion of the polytetrafluoroethylene layer 18 (FIG. 2) to expand rapidly while the top portion of the polytetrafluoroethylene layer 18 (FIG. 2) remains cool. The resultant forces are resolved by an upwards bending of the actuator 20 as illustrated in FIG. 1.

In a second operating mode, as illustrated in FIG. 1, the two heaters 12, 13 (FIG. 2) are activated causing an expansion of the PTFE layer 18 (FIG. 2) on one side while the other side remains cool. The resulting expansion provides for a movement of the actuator 20 to one side as illustrated in FIG. 1.

Finally, in FIG. 3, there is provided a further form of movement this time being up and to a side. This form of movement is activated by heating each of the resistive elements 11-13 (FIG. 2) which is resolved a movement of the actuator 20 up and to the side.

Hence, through the controlled use of the heater elements 11-13 (FIG. 2), the position of the end point 30 of the actuator 20 (FIG. 1) can be fully controlled. To this end the PTFE portion 18 is extended beyond the copper interconnect 14 so as to provide a generally useful end portion 30 for movement of objects to the like.

Turning to FIG. 4, there is illustrated an explosive perspective view of the construction of a single actuator. The actuator can be constructed utilising semi-conductor fabrication techniques and can be constructed on a wafer 42 or other form of substrate. On top of the wafer 42 is initially fabricated a sacrificial etch layer to form an underside portion utilising a mask shape of a actuator device. Next, a first layer of PTFE layer 64 is deposited followed by the bottom level copper heater level 45 forming the bottom two heaters. On top of this layer is formed a PTFE layer having vias for the interconnect 14. Next, a second copper layer 48 is provided for the top heater and common line with interconnection 14 to the bottom copper layer. On top of the copper layer 28 is provided a further polytetrafluoroethylene layer of layer 44 with the depositing of polytetrafluoroethylene layer 44 including the filling of the gaps, e.g. 49 in the return common line of the copper layer. The filling of the gaps allows for a significant reduction in the possibilities of laminar separation of the polytetrafluoroethylene layers from the copper layer.

The two copper layers also allow the routing of current drive lines to each actuator.

Hence, an array of actuators could be formed on a single wafer and activated together so as to move an object placed near the array. Each actuator in the array can then be utilised to provide a circular motion of its end tip. Initially, the actuator can be in a rest position and then moved to a side position as illustrated for actuator 20 in FIG. 1 then moved to an elevated side position as illustrated in FIG. 3 thereby engaging the object to be moved. The actuator can then be moved to nearly an elevated position as shown for actuator 20 in FIG. 1. This resulting in a corresponding force being applied to the object to be moved. Subsequently, the actuator is returned to its rest position and the cycle begins again. Utilising continuous cycles, an object can be made to move in accordance with requirements. Additionally, the reverse cycle can be utilised to move an object in the opposite direction.

Preferably, an array of actuators are utilised thereby forming the equivalent of a cilia array of actuators. Multiple cilia arrays can then be formed on a single semi-conductor wafer which is later diced into separate cilia arrays. Preferably, the actuators on each cilia array are divided into groups with adjacent actuators being in different groups. The cilia array can then be driven in four phases with one in four actuators pushing the object to be moved in each portion of the phase cycle.

Ideally, the cilia arrays can then be utilised to move an object, for example to move a card past an information sensing device in a controlled manner for reading information stored on the card. In another example, the cilia arrays can be utilised to move printing media past a printing head in an ink jet printing device. Further, the cilia arrays can be utilised for manipulating means in the field of nano technology, for example in atomic force microscopy (AFM).

Preferably, so as to increase the normally low coefficient of friction of PTFE, the PTFE end 20 is preferably treated by means of an ammonia plasma etch so as to increase the coefficient of friction of the end portion.

It would be evident to those skilled in the art that other arrangements maybe possible whilst still following in the scope of the present invention. For example, other materials and arrangements could be utilised. For example, a helical arrangement could be provided in place of the serpentine arrangement where a helical system is more suitable.

It would be appreciated by a person skilled in the art that numerous variations and/or modifications may be made to the present invention as shown in the specific embodiment without departing from the spirit or scope of the invention as broadly described. The present embodiment is, therefore, to be considered in all respects to be illustrative and not restrictive.

Ink Jet Technologies

The embodiments of the invention use an ink jet printer type device. Of course many different devices could be used. However presently popular ink jet printing technologies are unlikely to be suitable.

The most significant problem with thermal inkjet is power consumption. This is approximately 100 times that required for high speed, and stems from the energy-inefficient means of drop ejection. This involves the rapid boiling of water to produce a vapor bubble which expels the ink. Water has a very high heat capacity, and must be superheated in thermal inkjet applications. This leads to an efficiency of around 0.02%, from electricity input to drop momentum (and increased surface area) out.

The most significant problem with piezoelectric inkjet is size and cost. Piezoelectric crystals have a very small deflection at reasonable drive voltages, and therefore require a large area for each nozzle. Also, each piezoelectric actuator must be connected to its drive circuit on a separate substrate. This is not a significant problem at the current limit of around 300 nozzles per print head, but is a major impediment to the fabrication of pagewide print heads with 19,200 nozzles.

Ideally, the inkjet technologies used meet the stringent requirements of in-camera digital color printing and other high quality, high speed, low cost printing applications. To meet the requirements of digital photography, new inkjet technologies have been created. The target features include:

low power (less than 10 Watts)

high resolution capability (1,600 dpi or more)

photographic quality output

low manufacturing cost

small size (pagewidth times minimum cross section)

high speed (<2 seconds per page).

All of these features can be met or exceeded by the inkjet systems described below with differing levels of difficulty. 45 different inkjet technologies have been developed by the Assignee to give a wide range of choices for high volume manufacture. These technologies form part of separate applications assigned to the present Assignee as set out in the table below.

The inkjet designs shown here are suitable for a wide range of digital printing systems, from battery powered one-time use digital cameras, through to desktop and network printers, and through to commercial printing systems.

For ease of manufacture using standard process equipment, the print head is designed to be a monolithic 0.5 micron CMOS chip with MEMS post processing. For color photographic applications, the print head is 100 mm long, with a width which depends upon the inkjet type. The smallest print head designed is IJ38, which is 0.35 mm wide, giving a chip area of 35 square mm. The print heads each contain 19,200 nozzles plus data and control circuitry.

Ink is supplied to the back of the print head by injection molded plastic ink channels. The molding requires 50 micron features, which can be created using a lithographically micromachined insert in a standard injection molding tool. Ink flows through holes etched through the wafer to the nozzle chambers fabricated on the front surface of the wafer. The print head is connected to the camera circuitry by tape automated bonding.

Cross-Referenced Applications

The following table is a guide to cross-referenced patent applications filed concurrently herewith and discussed hereinafter with the reference being utilized in subsequent tables when referring to a particular case:

    ______________________________________                                               U.S. patent                                                              Docket                                                                               application                                                              No.   Ser. No.  Title                                                          ______________________________________                                         IJ01US                                                                               09/112,751                                                                               Radiant Plunger Ink Jet Printer                                IJ02US                                                                               09/112,787                                                                               Electrostatic Ink Jet Printer                                  IJ03US                                                                               09/112,802                                                                               Planar Thermoelastic Bend Actuator Ink Jet                     IJ04US                                                                               09/112,803                                                                               Stacked Electrostatic Ink Jet Printer                          IJ05US                                                                               09/113,097                                                                               Reverse Spring Lever Ink Jet Printer                           IJ06US                                                                               09/113,099                                                                               Paddle Type Ink Jet Printer                                    IJ07US                                                                               09/113,084                                                                               Permanent Magnet Electromagnetic Ink Jet Printer               IJ08US                                                                               09/113,066                                                                               Planar Swing Grill Electromagnetic Ink Jet Printer             IJ09US                                                                               09/112,778                                                                               Pump Action Refill Ink Jet Printer                             IJ10US                                                                               09/112,779                                                                               Pulsed Magnetic Field Ink Jet Printer                          IJ11US                                                                               09/113,077                                                                               Two Plate Reverse Firing Electromagnetic Ink Jet                               Printer                                                        IJ12US                                                                               09/113,061                                                                               Linear Stepper Actuator Ink Jet Printer                        IJ13US                                                                               09/112,818                                                                               Gear Driven Shutter Ink Jet Printer                            IJ14US                                                                               09/112,816                                                                               Tapered Magnetic Pole Electromagnetic Ink Jet                                  Printer                                                        IJ15US                                                                               09/112,772                                                                               Linear Spring Electromagnetic Grill Ink Jet Printer            IJ16US                                                                               09/112,819                                                                               Lorenz Diaphragm Electromagnetic Ink Jet Printer               IJ17US                                                                               09/112,815                                                                               PTFE Surface Shooting Shuttered Oscillating                                    Pressure Ink Jet Printer                                       IJ18US                                                                               09/113,096                                                                               Buckle Grip Oscillating Pressure Ink Jet Printer               IJ19US                                                                               09/113,068                                                                               Shutter Based Ink Jet Printer                                  IJ20US                                                                               09/113,095                                                                               Curling Calyx Thermoelastic Ink Jet Printer                    IJ21US                                                                               09/112,808                                                                               Thermal Actuated Ink Jet Printer                               IJ22US                                                                               09/112,809                                                                               Iris Motion Ink Jet Printer                                    IJ23US                                                                               09/112,780                                                                               Direct Firing Thermal Bend Actuator Ink Jet                                    Printer                                                        IJ24US                                                                               09/113,083                                                                               Conductive PTFE Ben Activator Vented Ink Jet                                   Printer                                                        IJ25US                                                                               09/113,121                                                                               Magnetostrictive Ink Jet Printer                               IJ26US                                                                               09/113,122                                                                               Shape Memory Alloy Ink Jet Printer                             IJ27US                                                                               09/112,793                                                                               Buckle Plate Ink Jet Printer                                   IJ28US                                                                               09/112,794                                                                               Thermal Elastic Rotary Impeller Ink Jet Printer                IJ29US                                                                               09/113,128                                                                               Thermoelastic Bend Actuator Ink Jet Printer                    IJ30US                                                                               09/113,127                                                                               Thermoelastic Bend Actuator Using PTFE and                                     Corrugated Copper Ink Jet Printer                              IJ31US                                                                               09/112,756                                                                               Bend Actuator Direct Ink Supply Ink Jet Printer                IJ32US                                                                               09/112,755                                                                               A High Young's Modulus Thermoelastic Ink Jet                                   Printer                                                        IJ33US                                                                               09/112,754                                                                               Thermally actuated slotted chamber wall ink jet                                printer                                                        IJ34US                                                                               09/112,811                                                                               Ink Jet Printer having a thermal actuator                                      comprising an external coiled spring                           IJ35US                                                                               09/112,812                                                                               Trough Container Ink Jet Printer                               IJ36US                                                                               09/112,813                                                                               Dual Chamber Single Vertical Actuator Ink Jet                  IJ37US                                                                               09/112,814                                                                               Dual Nozzle Single Horizontal Fulcrum Actuator                                 Ink Jet                                                        IJ38US                                                                               09/112,764                                                                               Dual Nozzle Single Horizontal Actuator Ink Jet                 IJ39US                                                                               09/112,765                                                                               A single bend actuator cupped paddle ink jet                                   printing device                                                IJ40US                                                                               09/112,767                                                                               A thermally actuated ink jet printer having a series                           of thermal actuator units                                      IJ41US                                                                               09/112,768                                                                               A thermally actuated ink jet printer including a                               tapered heater element                                         IJ42US                                                                               09/112,807                                                                               Radial Back-Curling Thermoelastic Ink Jet                      IJ43US                                                                               09/112,806                                                                               Inverted Radial Back-Curling Thermoelastic Ink                                 Jet                                                            IJ44US                                                                               09/112,820                                                                               Surface bend actuator vented ink supply ink jet                                printer                                                        IJ45US                                                                               09/112,821                                                                               Coil Actuated Magnetic Plate Ink Jet Printer                   ______________________________________                                    

Tables of Drop-on-Demand Inkjets

Eleven important characteristics of the fundamental operation of individual inkjet nozzles have been identified. These characteristics are largely orthogonal, and so can be elucidated as an eleven dimensional matrix. Most of the eleven axes of this matrix include entries developed by the present assignee.

The following tables form the axes of an eleven dimensional table of inkjet types.

Actuator mechanism (18 types)

Basic operation mode (7 types)

Auxiliary mechanism (8 types)

Actuator amplification or modification method (17 types)

Actuator motion (19 types)

Nozzle refill method (4 types)

Method of restricting back-flow through inlet (10 types)

Nozzle clearing method (9 types)

Nozzle plate construction (9 types)

Drop ejection direction (5 types)

Ink type (7 types)

The complete eleven dimensional table represented by these axes contains 36.9 billion possible configurations of inkjet nozzle. While not all of the possible combinations result in a viable inkjet technology, many million configurations are viable. It is clearly impractical to elucidate all of the possible configurations. Instead, certain inkjet types have been investigated in detail. These are designated IJ01 to IJ45 above.

Other inkjet configurations can readily be derived from these 45 examples by substituting alternative configurations along one or more of the 11 axes. Most of the IJ01 to IJ45 examples can be made into inkjet print heads with characteristics superior to any currently available inkjet technology.

Where there are prior art examples known to the inventor, one or more of these examples are listed in the examples column of the tables below. The IJ01 to IJ45 series are also listed in the examples column. In some cases, a printer may be listed more than once in a table, where it shares characteristics with more than one entry.

Suitable applications include: Home printers, Office network printers, Short run digital printers, Commercial print systems, Fabric printers, Pocket printers, Internet WWW printers, Video printers, Medical imaging, Wide format printers, Notebook PC printers, Fax machines, Industrial printing systems, Photocopiers, Photographic minilabs etc.

The information associated with the aforementioned 11 dimensional matrix are set out in the following tables.

    __________________________________________________________________________     ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS)                        __________________________________________________________________________     Actuator                                                                       Mechanism                                                                             Description       Advantages                                            __________________________________________________________________________     Thermal                                                                               An electrothermal heater heats the                                                               ♦ Large force generated                 bubble ink to above boiling point,                                                                      ♦ Simple construction                          transferring significant heat to the                                                             ♦ No moving parts                              aqueous ink. A bubble nucleates and                                                              ♦ Fast operation                               quickly forms, expelling the ink.                                                                ♦ Small chip area required for                 The efficiency of the process is low,                                                               actuator                                                  with typically less than 0.05% of the                                          electrical energy being transformed                                            into kinetic energy of the drop.                                        Piezoelectric                                                                         A piezoelectric crystal such as lead                                                             ♦ Low power consumption                        lanthanum zirconate (PZT) is                                                                     ♦ Many ink types can be used                   electrically activated, and either                                                               ♦ Fast operation                               expands, shears, or bends to apply                                                               ♦ High efficiency                              pressure to the ink, ejecting drops.                                    Electro-                                                                              An electric field is used to activate                                                            ♦ Low power consumption                 strictive                                                                             electrostriction in relaxor materials                                                            ♦ Many ink types can be used                   such as lead lanthanum zirconate                                                                 ♦ Low thermal expansion                        titanate (PLZT) or lead magnesium                                                                ♦ Electric field strength                      niobate (PMN).       required (approx. 3.5 V/μm)                                                 can be generated without                                                       difficulty                                                                  ♦ Does not require electrical                                       poling                                             Ferroelectric                                                                         An electric field is used to induce a                                                            ♦ Low power consumption                        phase transition between the                                                                     ♦ Many ink types can be used                   antiferroelectric (AFE) and                                                                      ♦ Fast operation (<1 μs)                    ferroelectric (FE) phase. Perovskite                                                             ♦ Relatively high longitudinal                 materials such as tin modified lead                                                                 strain                                                    lanthanum zirconate titanate                                                                     ♦ High efficiency                              (PLZSnT) exhibit large strains of up                                                             ♦ Electric field strength of                   to 1% associated with the AFE to FE                                                                 around 3 V/μm can be                                   phase transition.    readily provided                                   Electrostatic                                                                         Conductive plates are separated by a                                                             ♦ Low power consumption                 plates compressible or fluid dielectric                                                                 ♦ Many ink types can be used                   (usually air). Upon application of a                                                             ♦ Fast operation                               voltage, the plates attract each other                                         and displace ink, causing drop                                                 ejection. The conductive plates may                                            be in a comb or honeycomb                                                      structure, or stacked to increase the                                          surface area and therefore the force.                                   Electrostatic                                                                         A strong electric field is applied to                                                            ♦ Low current consumption               pull on ink                                                                           the ink, whereupon electrostatic                                                                 ♦ Low temperature                              attraction accelerates the ink towards                                         the print medium.                                                       Permanent                                                                             An electromagnet directly attracts a                                                             ♦ Low power consumption                 magnet permanent magnet, displacing ink                                                                 ♦ Many ink types can be used            electro-                                                                              and causing drop ejection. Rare earth                                                            ♦ Fast operation                        magnetic                                                                              magnets with a field strength around                                                             ♦ High efficiency.                             1 Tesla can be used. Examples are:                                                               ♦ Easy extension from single                   Samarium Cobalt (SaCo) and                                                                          nozzles to pagewidth print                                magnetic materials in the                                                                           heads                                                     neodymium iron boron family                                                    (NdFeB, NdDyFeBNb, NdDyFeB,                                                    etc)                                                                    Soft magnetic                                                                         A solenoid induced a magnetic field                                                              ♦ Low power consumption                 core electro-                                                                         in a soft magnetic core or yoke                                                                  ♦ Many ink types can be used            magnetic                                                                              fabricated from a ferrous material                                                               ♦ Fast operation                               such as electroplated iron alloys such                                                           ♦ High efficiency                              as CoNiFe [1], CoFe, or NiFe alloys.                                                             ♦ Easy extension from single                   Typically, the soft magnetic material                                                               nozzles to pagewidth print                                is in two parts, which are normally                                                                 heads                                                     held apart by a spring. When the                                               solenoid is actuated, the two parts                                            attract, displacing the ink.                                            Magnetic                                                                              The Lorenz force acting on a current                                                             ♦ Low power consumption                 Lorenz force                                                                          carrying wire in a magnetic field is                                                             ♦ Many ink types can be used                   utilized.         ♦ Fast operation                               This allows the magnetic field to be                                                             ♦ High efficiency                              supplied externally to the print head,                                                           ♦ Easy extension from single                   for example with rare earth                                                                         nozzles to pagewidth print                                permanent magnets.                                                                                  heads                                                     Only the current carrying wire need                                            be fabricated on the print-head,                                               simplifying materials requirements.                                     Magneto-                                                                              The actuator uses the giant                                                                      ♦ Many ink types can be used            striction                                                                             magnetostrictive effect of materiats                                                             ♦ Fast operation                               such as Terfenol-D (an alloy of                                                                  ♦ Easy extension from single                   terbium, dysprosium and iron                                                                        nozzles to pagewidth print                                developed at the Naval Ordnance                                                                     heads                                                     Laboratory, hence Ter-Fe-NOL). For                                                               ♦ High force is available                      best efficiency, the actuator should                                           be pre-stressed to approx. 8 MPa.                                       Surface                                                                               Ink under positive pressure is held in                                                           ♦ Low power consumption                 tension                                                                               a nozzle by surface tension. The                                                                 ♦ Simple construction                   reduction                                                                             surface tension of the ink is reduced                                                            ♦ No unusual materials                         below the bubble threshold, causing                                                                 required in fabrication                                   the ink to egress from the nozzle.                                                               ♦ High efficiency                                                ♦ Easy extension from single                                        nozzles to pagewidth print                                                     heads                                              Viscosity                                                                             The ink viscosity is locally reduced                                                             ♦ Simple construction                   reduction                                                                             to select which drops are to be                                                                  ♦ No unusual materials                         ejected. A viscosity reduction can be                                                               required in fabrication                                   achieved electrothermally with most                                                              ♦ Easy extension from single                   inks, but special inks can be                                                                       nozzles to pagewidth print                                engineered for a 100:1 viscosity                                                                    heads                                                     reduction.                                                              Acoustic                                                                              An acoustic wave is generated and                                                                ♦ Can operate without a                        focussed upon the drop ejection                                                                     nozzle plate                                              region.                                                                 Thermoelastic                                                                         An actuator which relies upon                                                                    ♦ Low power consumption                 bend actuator                                                                         differential thermal expansion upon                                                              ♦ Many ink types can be used                   Joule heating is used.                                                                           ♦ Simple planar fabrication                                      ♦ Small chip area required for                                      each actuator                                                               ♦ Fast operation                                                 ♦ High efficiency                                                ♦ CMOS compatible voltages                                         and currents                                                                 ♦ Standard MEMS processes                                           can be used                                                                 ♦ Easy extension from single                                        nozzles to pagewidth print                                                     heads                                              High CTE                                                                              A material with a very high                                                                      ♦ High force can be generated           thermoelastic                                                                         coefficient of thermal expansion                                                                 ♦ PTFE is a candidate for low           actuator                                                                              (CTE) such as        dielectric constant                                       polytetrafluoroethylene (PTFE) is                                                                   insulation in ULSI                                        used. As high CTE materials are                                                                  ♦ Very low power                               usually non-conductive, a heater                                                                    consumption                                               fabricated from a conductive                                                                     ♦ Many ink types can be used                   material is incorporated. A 50 μm                                                             ♦ Simple planar fabrication                    long PTFE bend actuator with                                                                     ♦ Small chip area required for                 polysilicon heater and 15 mW power                                                                  each actuator                                             input can provide 180 μN force and                                                            ♦ Fast operation                               10 μm deflection. Actuator motions                                                            ♦ High efficiency                              include:          ♦ CMOS compatible voltages                     1) Bend              and currents                                              2) Push           ♦ Easy extension from single                   3) Buckle            nozzles to pagewidth print                                4) Rotate            heads                                              Conductive                                                                            A polymer with a high coefficient of                                                             ♦ High force can be generated           polymer                                                                               thermal expansion (such as PTFE) is                                                              ♦ Very low power                        thermoelastic                                                                         doped with conducting substances to                                                                 consumption                                        actuator                                                                              increase its conductivity to about 3                                                             ♦ Many ink types can be used                   orders of magnitude below that of                                                                ♦ Simple planar fabrication                    copper. The conducting polymer                                                                   ♦ Small chip area required for                 expands when resistively heated.                                                                    each actuator                                             Examples of conducting dopants                                                                   ♦ Fast operation                               include:          ♦ High efficiency                              1) Carbon nanotubes                                                                              ♦ CMOS compatible voltages                     2) Metal fibers      and currents                                              3) Conductive polymers such as                                                                   ♦ Easy extension from single                   doped polythiophene                                                                                 nozzles to pagewidth print                                4) Carbon granules                                                                                  heads                                              Shape memory                                                                          A shape memory alloy such as TiNi                                                                ♦ High force is available               alloy  (also known as Nitinol - Nickel                                                                     (stresses of hundreds of                                  Titanium alloy developed at the                                                                     MPa)                                                      Naval Ordnance Laboratory) is                                                                    ♦ Large strain is available                    thermally switched between its weak                                                                 (more than 3%)                                            martensitic state and its high                                                                   ♦ High corrosion resistance                    stiffness austenic state. The shape of                                                           ♦ Simple construction                          the actuator in its martensitic state is                                                         ♦ Easy extension from single                   deformed relative to the austenic                                                                   nozzles to pagewidth print                                shape. The shape change causes                                                                      heads                                                     ejection of a drop.                                                                              ♦ Low voltage operation                 Linear Linear magnetic actuators include                                                                ♦ Linear Magnetic actuators             Magnetic                                                                              the Linear Induction Actuator (LIA),                                                                can be constructed with                            Actuator                                                                              Linear Permanent Magnet                                                                             high thrust, long travel, and                             Synchronous Actuator (LPMSA),                                                                       high efficiency using planar                              Linear Reluctance Synchronous                                                                       semiconductor fabrication                                 Actuator (LRSA), Linear Switched                                                                    techniques                                                Reluctance Actuator (LSRA), and                                                                  ♦ Long actuator travel is                      the Linear Stepper Actuator (LSA).                                                                  available                                                                   ♦ Medium force is available                                      ♦ Low voltage operation                 __________________________________________________________________________     Actuator                                                                       Mechanism                                                                             Disadvantages     Examples                                              __________________________________________________________________________     Thermal                                                                               ♦ High power                                                                       ♦ Canon Bubblejet                       bubble ♦ Ink carrier limited to water                                                        1979 Endo et al GB                                        ♦ Low efficiency                                                                      patent 2,007,162                                          ♦ High temperatures required                                                       ♦ Xerox heater-in-pit                          ♦ High mechanical stress                                                              1990 Hawkins et al                                        ♦ Unusual materials required                                                          U.S. Pat. No. 4,899,181                                   ♦ Large drive transistors                                                          ♦ Hewlett-Packard TIJ                          ♦ Cavitation causes actuator failure                                                  1982 Vaught et al                                         ♦ Kogation reduces bubble formation                                                   U.S. Pat. No. 4,490,728                                   ♦ Large print heads are difficult to                                fabricate                                                            Piezoelectric                                                                         ♦ Very large area required for actuator                                            ♦ Kyser et al U.S. Pat. No.                    ♦ Difficult to integrate with electronics                                             3,946,398                                                 ♦ High voltage drive transistors required                                          ♦ Zoltan U.S. Pat. No.                         ♦ Full pagewidth print heads impractical                                              3,683,212                                                    due to actuator size                                                                          ♦ 1973 Stemme U.S. Pat. No.                    ♦ Requires electrical poling in high                                                  3,747,120                                                    strengths during manufacture                                                                  ♦ Epson Stylus                                                   ♦ Tektronix                                                      ♦ IJ04                                  Electro-                                                                              ♦ Low maximum strain (approx. 0.01%)                                               ♦ Seiko Epson, Usui et                  strictive                                                                             ♦ Large area required for actuator due                                                all JP 253401/96                                             low strain     ♦ IJ04                                         ♦ Response speed is marginal (˜10 μs)                   ♦ High voltage drive transistors required                        ♦ Full pagewidth print heads impractical                            due to actuator size                                                 Ferroelectric                                                                         ♦ Difficult to integrate with electronics                                          ♦ IJ04                                         ♦ Unusual materials such as PLZSnT are                              required                                                                    ♦ Actuators require a large area                          Electrostatic                                                                         ♦ Difficult to operate electrostatic                                               ♦ IJ02, IJ04                            plates    devices in an aqueous environment                                           ♦ The electrostatic actuator will normally                          need to be separated from the ink                                           ♦ Very large area required to achieve                               high forces                                                                 ♦ High voltage drive transistors may be                             required                                                                    ♦ Full pagewidth print heads are not                                competitive due to actuator size                                     Electrostatic                                                                         ♦ High voltage required                                                            ♦ 1989 Saito et al,                     pull on ink                                                                           ♦ May be damaged by sparks due to air                                                 U.S. Pat. No. 4,799,068                                      breakdown      ♦ 1989 Miura et al,                            ♦ Required field strength increases as                                                U.S. Pat. No. 4,810,954                                      drop size decreases                                                                           ♦ Tone-jet                                     ♦ High voltage drive transistors required                        ♦ Electrostatic field attracts dust                       Permanent                                                                             ♦ Complex fabrication                                                              ♦ IJ07, IJ10                            magnet ♦ Permanent magnetic material such as                     electro-                                                                                 Neodymium Iron Boron (NdFeB)                                         magnetic                                                                                 required.                                                                   ♦ High local currents required                                   ♦ Copper metalization should be used for                            long electromigration lifetime and low                                         resistivity                                                                 ♦ Pigmented inks are usually infeasible                          ♦ Operating temperature limited to the                              Curie temperature (around 540 K)                                     Soft magnetic                                                                         ♦ Complex fabrication                                                              ♦ IJ01, IJ05, IJ08, IJ10                core electro-                                                                         ♦ Materials not usually present in                                                 ♦ IJ12, IJ14, IJ15, IJ17                magnetic                                                                                 CMOS fab such as NiFe, CoNiFe, or                                              CoFe are required                                                           ♦ High local currents required                                   ♦ Copper metalization should be used for                            long electromigration lifetime and low                                         resistivity                                                                 ♦ Electroplating is required                                     ♦ High saturation flux density is required                          (2.0-2.1 T is achievable with CoNiFe                                           [1])                                                                 Magnetic                                                                              ♦ Force acts as a twisting motion                                                  ♦ IJ06, IJ11, IJ13, IJ16                Lorenz force                                                                          ♦ Typically, only a quarter of the                                  solenoid length provides force in a                                            useful direction                                                            ♦ High local currents required                                   ♦ Copper metalization should be used for                            long electromigration lifetime and low                                         reistivity                                                                  ♦ Pigmented inks are usually infeasible                   Magneto-                                                                              ♦ Force acts as a twisting motion                                                  ♦ Fischenbeck, U.S. Pat. No.            striction                                                                             ♦ Unusual materials such as Terfenol-D                                                4,032,929                                                    are required   ♦ IJ25                                         ♦ High local currents required                                   ♦ Copper metalization should be used for                            long electromigration lifetime and low                                         resistivity                                                                 ♦ Pre-stressing may be required                           Surface                                                                               ♦ Requires supplementary force to effect                                           ♦ Silverbrook, EP 0771                  tension                                                                                  drop separation                                                                                  658 A2 and related                                 reduction                                                                             ♦ Requires special ink surfactants                                                    patent applications                                       ♦ Speed may be limmited by surfactant                               properties                                                           Viscosity                                                                             ♦ Requires supplementary force to effect                                           ♦ Silverbrook, EP 0771                  reduction                                                                                drop separation                                                                                  658 A2 and related                                        ♦ Requires special ink viscosity                                                      patent applications                                          properties                                                                  ♦ High speed is difficult to achieve                             ♦ Requires oscillating ink pressure                              ♦ A high temperature difference                                     (typically 80 degrees) is required                                   Acoustic                                                                              ♦ Complex drive circuitry                                                          ♦ 1993 Hadimioglu et                           ♦ Complex fabrication                                                                 al, EUP 550,192                                           ♦ Low efficiency                                                                   ♦ 1993 Elrod et al, EUP                        ♦ Poor control of drop position                                                       572,220                                                   ♦ Poor control of drop volume                             Thermoelastic                                                                         ♦ Efficient aqueous operation requires                                             ♦ IJ03, IJ09, IJ17, IJ18                bend actuator                                                                            thermal insulator on the hot side                                                             ♦ IJ19, IJ20, IJ21, IJ22                       ♦ Corrosion prevention can be difficult                                            ♦ IJ23, IJ24, IJ27, IJ28                       ♦ Pigmented inks may be infeasible,                                                ♦ IJ29, IJ30, IJ31, IJ32                          pigment particles may jam the bend                                                            ♦ IJ33, IJ34, IJ35, IJ36                          actuator       ♦ IJ37, IJ38, IJ39, IJ40                                         ♦ IJ41                                  High CTE                                                                              ♦ Requires special material (e.g. PTFE)                                            ♦ IJ09, IJ17, IJ18, IJ20                thermoelastic                                                                         ♦ Requires a PTFE deposition process,                                              ♦ IJ21, IJ22, IJ23, IJ24                actuator                                                                                 which is not yet standard in ULSI fabs                                                        ♦ IJ27, IJ28, IJ29, IJ30                       ♦ PTFE deposition cannot be followed                                               ♦ IJ31, IJ42, IJ43, IJ44                          with high temperature (above 350° C.)                                   processing                                                                  ♦ Pigmented inks may be infeasible, as                              pigment particles may jam the bend                                             actuator                                                             Conductive                                                                            ♦ Requires special materials                                                       ♦ IJ24                                  polymer                                                                                  development (High CTE conductive                                     thermoelastic                                                                            polymer)                                                             actuator                                                                              ♦ Requires a PTFE deposition process,                               which is not yet standard in ULSI fabs                                      ♦ PTFE deposition cannot be followed                                with high temperature (above 350° C.)                                   processing                                                                  ♦ Evaporation and CVD deposition                                    techniques cannot be used                                                   ♦ Pigmented inks may be infeasible, as                              pigment particles may jam the bend                                             actuator                                                             Shape memory                                                                          ♦ Fatigue limits maximum number of                                                 ♦ IJ26                                  alloy     cycles                                                                      ♦ Low strain (1%) is required to extend                             fatigue resistance                                                          ♦ Cycle rate limited by heat removal                             ♦ Requires unusual materials (TiNi)                              ♦ The latent heat of transformation must                            be provided                                                                 ♦ High current operation                                         ♦ Requires pre-stressing to distort the                             martensitic state                                                    Linear ♦ Requires unusual semiconductor                                                   ♦ IJ12                                  Magnetic                                                                                 materials such as soft magnetic alloys                               Actuator                                                                                 (e.g. CoNiFe [1])                                                           ♦ Some varieties also require permanent                             magnetic materials such as                                                     Neodymium iron boron (NdFeB)                                                ♦ Requires complex multi-phase drive                                circuitry                                                                   ♦ High current operation                                  __________________________________________________________________________

    __________________________________________________________________________     BASIC OPERATION MODE                                                           __________________________________________________________________________     Operational                                                                    mode   Description       Advantages                                            __________________________________________________________________________     Actuator                                                                              This is the simplest mode of                                                                     ♦ Simple operation                      directly                                                                              operation: the actuator directly                                                                 ♦ No external fields required           pushes ink                                                                            supplies sufficient kinetic energy to                                                            ♦ Satellite drops can be                       expel the drop. The drop must have a                                                                avoided if drop velocity is                               sufficient velocity to overcome the                                                                 less than 4 m/s                                           surface tension.  ♦ Can be efficient, depending                                       upon the actuator used                             Proximity                                                                             The drops to be printed are selected                                                             ♦ Very simple print head                       by some manner (e.g. thermally                                                                      fabrication can be used                                   induced surface tension reduction of                                                             ♦ The drop selection means                     pressurized ink). Selected drops are                                                                does not need to provide the                              separated from the ink in the nozzle                                                                energy required to separate                               by contact with the print medium, or                                                                the drop from the nozzle                                  a transfer roller.                                                      Electrostatic                                                                         The drops to be printed are selected                                                             ♦ Very simple print head                pull on ink                                                                           by some manner (e.g. thermally                                                                      fabrication can be used                                   induced surface tension reduction of                                                             ♦ The drop selection means                     pressurized ink). Selected drops are                                                                does not need to provide the                              separated from the ink in the nozzle                                                                energy required to separate                               by a strong electric field.                                                                         the drop from the nozzle                           Magnetic pull                                                                         The drops to be printed are selected                                                             ♦ Very simple print head                on ink by some manner (e.g. thermally                                                                      fabrication can be used                                   induced surface tension reduction of                                                             ♦ The drop selection means                     pressurized ink). Selected drops are                                                                does not need to provide the                              separated from the ink in the nozzle                                                                energy required to separate                               by a strong magnetic field acting on                                                                the drop from the nozzle                                  the magnetic ink.                                                       Shutter                                                                               The actuator moves a shutter to                                                                  ♦ High speed (>50 KHz)                         block ink flow to the nozzle. The ink                                                               operation can be achieved                                 pressure is pulsed at a multiple of the                                                             due to reduced refill time                                drop ejection frequency.                                                                         ♦ Drop timing can be very                                           accurate                                                                    ♦ The actuator energy can be                                        very low                                           Shuttered grill                                                                       The actuator moves a shutter to                                                                  ♦ Actuators with small travel                  block ink flow through a grill to the                                                               can be used                                               nozzle. The shutter movement need                                                                ♦ Actuators with small force                   only be equal to the width of the grill                                                             can be used                                               holes.            ♦ High speed (>50 KHz)                                              operation can be achieved                          Pulsed A pulsed magnetic field attracts an                                                              ♦ Extremely low energy                  magnetic pull                                                                         `ink pusher` at the drop ejection                                                                   operation is possible                              on ink pusher                                                                         frequency. An actuator controls a                                                                ♦ No heat dissipation                          catch, which prevents the ink pusher                                                                problems                                                  from moving when a drop is not to                                              be ejected.                                                             __________________________________________________________________________     Operational                                                                    mode   Disadvantages     Examples                                              __________________________________________________________________________     Actuator                                                                              ♦ Drop repetition rate is usually limited                                          ♦ Thermal inkjet                        directly                                                                                 to less than 10 KHz. However, this is                                                         ♦ Piezoelectric inkjet                  pushes ink                                                                               not fundamental to the method, but is                                                         ♦ IJ01, IJ02, IJ03, IJ04                          related to the refill method normally                                                         ♦ IJ05, IJ06, IJ07, IJ09                          used           ♦ IJ11, IJ12, IJ14, IJ16                       ♦ All of the drop kinetic energy must                                              ♦ IJ20, IJ22, IJ23, IJ24                          provided by the actuator                                                                      ♦ IJ25, IJ26, IJ27, IJ28                       ♦ Satellite drops usually form if drop                                             ♦ IJ29, IJ30, IJ31, IJ32                          velocity is greater than 4.5 m/s                                                              ♦ IJ33, IJ34, IJ35, IJ36                                         ♦ IJ37, IJ38, IJ39, IJ40                                         ♦ IJ41, IJ42, IJ43, IJ44                Proximity                                                                             ♦ Requires close proximity between                                                 ♦ Silverbrook, EP 0771                            print head and the print media or                                                                658 A2 and related                                           transfer roller                                                                                  patent applications                                       ♦ May require two print heads printing                              alternate rows of the image                                                 ♦ Monolithic color print heads are                                  difficult                                                            Electrostatic                                                                         ♦ Requires very high electrostatic                                                 ♦ Silverbrook, EP 0771                  pull on ink                                                                           ♦ Electrostatic field for small nozzle                                                658 A2 and related                                           sizes is above air breakdown                                                                     patent applications                                       ♦ Electrostatic field may attract dust                                             ♦ Tone-Jet                              Magnetic pull                                                                         ♦ Requires magnetic ink                                                            ♦ Silverbrook, EP 0771                  on ink ♦ Ink colors other than black are difficult                                           658 A2 and related                                        ♦ Requires very high magnetic fields                                                  patent applications                                Shutter                                                                               ♦ Moving parts are required                                                        ♦ IJ13, IJ17, IJ21                             ♦ Requires ink pressure modulator                                ♦ Friction and wear must be considered                           ♦ Stiction is possible                                    Shuttered grill                                                                       ♦ Moving parts are required                                                        ♦ IJ08, IJ15, IJ18, IJ19                       ♦ Requires ink pressure modulator                                ♦ Friction and wear must be considered                           ♦ Stiction is possible                                    Pulsed ♦ Requires an external pulsed magnetic                                             ♦ IJ10                                  magnetic pull                                                                            field                                                                on ink pusher                                                                         ♦ Requires special materials for both the                           actuator and the ink pusher                                                 ♦ Complex construction                                    __________________________________________________________________________

    __________________________________________________________________________     AUXILIARY MECHANISM (APPLIED TO ALL NOZZLES)                                   __________________________________________________________________________     Auxiliary                                                                      Mechanism                                                                             Description       Advantages                                            __________________________________________________________________________     None   The actuator directly fires the ink                                                              ♦ Simplicity of construction                   drop, and there is no external field or                                                          ♦ Simplicity of operation                      other mechanism required.                                                                        ♦ Small physical size                   Oscillating ink                                                                       The ink pressure oscillates,                                                                     ♦ Oscillating ink pressure can          pressure                                                                              providing much of the drop ejection                                                                 provide a refill pulse,                            (including                                                                            energy. The actuator selects which                                                                  allowing higher operating                          acoustic                                                                              drops are to be fired by selectively                                                                speed                                              stimulation)                                                                          blocking or enabling nozzles. The                                                                ♦ The actuators may operate                    ink pressure oscillation may be                                                                     with much lower energy                                    achieved by vibrating the print head,                                                            ♦ Acoustic lenses can be used                  or preferably by an actuator in the                                                                 to focus the sound on the                                 ink supply.          nozzles                                            Media  The print head is placed in close                                                                ♦ Low power                             proximity                                                                             proximity to the print medium.                                                                   ♦ High accuracy                                Selected drops protrude from the                                                                 ♦ Simple print head                            print head further than unselected                                                                  construction                                              drops, and contact the print medium.                                           The drop soaks into the medium fast                                            enough to cause drop separation.                                        Transfer roller                                                                       Drops are printed to a transfer roller                                                           ♦ High accuracy                                instead of straight to the print                                                                 ♦ Wide range of print                          medium. A transfer roller can also be                                                               substrates can be used                                    used for proximity drop separation.                                                              ♦ Ink can be dried on the                                          transfer roller                                     Electrostatic                                                                         An electric field is used to accelerate                                                          ♦ Low power                                    selected drops towards the print                                                                 ♦ Simple print head                            medium.              construction                                       Direct A magnetic field is used to accelerate                                                           ♦ Low power                             magnetic field                                                                        selected drops of magnetic ink                                                                   ♦ Simple print head                            towards the print medium.                                                                           construction                                       Cross  The print head is placed in a constant                                                           ♦ Does not require magnetic             magnetic field                                                                        magnetic field. The Lorenz force in a                                                               materials to be integrated in                             current carrying wire is used to move                                                               the print head                                            the actuator.        manufacturing process                              Pulsed A pulsed magnetic field is used to                                                               ♦ Very low power operation              magnetic field                                                                        cyclically attract a paddle, which                                                                  is possible                                               pushes on the ink. A small actuator                                                              ♦ Small print head size                        moves a catch, which selectively                                               prevents the paddle from moving.                                        __________________________________________________________________________     Auxiliary                                                                      Mechanism                                                                             Disadvantages     Examples                                              __________________________________________________________________________     None   ♦ Drop ejection energy must be supplied                                            ♦ Most inkjets,                                   by individual nozzle actuator                                                                    including                                                                      piezoelectric and                                                              thermal bubble.                                                             ♦ IJ01-IJ07, IJ09, IJ11                                          ♦ IJ12, IJ14, IJ20, IJ22                                         ♦ IJ23-IJ45                             Oscillating ink                                                                       ♦ Requires external ink pressure                                                   ♦ Silverbrook, EP 0771                  pressure                                                                                 oscillator        658 A2 and related                                 (including                                                                            ♦ Ink pressure phase and amplitude                                                    patent applications                                acoustic                                                                                 be carefully controlled                                                                       ♦ IJ08, IJ13, IJ15, IJ17                stimulation)                                                                          ♦ Acoustic reflections in the ink chamber                                          ♦ IJ18, IJ19, IJ21                                must be designed for                                                 Media  ♦ Precision assembly required                                                      ♦ Silverbrook, EP 0771                  proximity                                                                             ♦ Paper fibers may cause problems                                                     658 A2 and related                                        ♦ Cannot print on rough substrates                                                    patent applications                                Transfer roller                                                                       ♦ Bulky                                                                            ♦ Silverbrook, EP 0771                         ♦ Expensive                                                                           658 A2 and related                                        ♦ Complex construction                                                                patent applications                                                         ♦ Tektronix hot melt                                                piezoelectric inkjet                                                        ♦ Any of the IJ series                  Electrostatic                                                                         ♦ Field strength required for separation                                           ♦ Silverbrook, EP 0771                            of small drops is near or above air                                                              658 A2 and related                                           breakdown         patent applications                                                         ♦ Tone-Jet                              Direct ♦ Requires magnetic ink                                                            ♦ Silverbrook, EP 0771                  magnetic field                                                                        ♦ Requires strong magnetic field                                                      658 A2 and related                                                             patent applications.                               Cross  ♦ Requires external magnet                                                         ♦ IJ06, IJ16                            magnetic field                                                                        ♦ Current densities may be high,                                    resulting in electromigration problems                               Pulsed ♦ Complex print head construction                                                  ♦ IJ10                                  magnetic field                                                                        ♦ Magnetic materials required in print                              head                                                                 __________________________________________________________________________

    __________________________________________________________________________     ACTUATOR AMPLIFICATION OR MODIFICATION METHOD                                  __________________________________________________________________________     Actuator                                                                       amplification                                                                         Description       Advantages                                            __________________________________________________________________________     None   No actuator mechanical                                                                           ♦ Operational simplicity                       amplification is used. The actuator                                            directly drives the drop ejection                                              process.                                                                Differential                                                                          An actuator material expands more                                                                ♦ Provides greater travel in a          expansion                                                                             on one side than on the other. The                                                                  reduced print head area                            bend actuator                                                                         expansion may be thermal,                                                                        ♦ The bend actuator converts                   piezoelectric, magnetostrictive, or                                                                 a high force low travel                                   other mechanism.     actuator mechanism to high                                                     travel, lower force                                                            mechanism.                                         Transient bend                                                                        A trilayer bend actuator where the                                                               ♦ Very good temperature                 actuator                                                                              two outside layers are identical. This                                                              stability                                                 cancels bend due to ambient                                                                      ♦ High speed, as a new drop                    temperature and residual stress. The                                                                can be fired before heat                                  actuator only responds to transient                                                                 dissipates                                                heating of one side or the other.                                                                ♦ Cancels residual stress of                                        formation                                          Actuator stack                                                                        A series of thin actuators are stacked.                                                          ♦ Increased travel                             This can be appropriate where                                                                    ♦ Reduced drive voltage                        actuators require high electric field                                          strength, such as electrostatic and                                            piezoelectric actuators.                                                Multiple                                                                              Multiple smaller actuators are used                                                              ♦ Increases the force available         actuators                                                                             simultaneously to move the ink.                                                                     from an actuator                                          Each actuator need provide only a                                                                ♦ Multiple actuators can be                    portion of the force required.                                                                      positioned to control ink                                                      flow accurately                                    Linear Spring                                                                         A linear spring is used to transform a                                                           ♦ Matches low travel actuator                  motion with small travel and high                                                                   with higher travel                                        force into a longer travel, lower force                                                             requirements                                              motion.           ♦ Non-contact method of                                            motion transformation                               Reverse spring                                                                        The actuator loads a spring. When                                                                ♦ Better coupling to the ink                   the actuator is turned off, the spring                                         releases. This can reverse the                                                 force/distance curve of the actuator                                           to make it compatible with the                                                 force/time requirements of the drop                                            ejection.                                                               Coiled A bend actuator is coiled to provide                                                             ♦ Increases travel                      actuator                                                                              greater travel in a reduced chip area.                                                           ♦ Reduces chip area                                              ♦ Planar implementations are                                        relatively easy to fabricate.                      Flexure bend                                                                          A bend actuator has a small region                                                               ♦ Simple means of increasing            actuator                                                                              near the fixture point, which flexes                                                                travel of a bend actuator                                 much more readily than the                                                     remainder of the actuator. The                                                 actuator flexing is effectively                                                converted from an even coiling to an                                           angular bend, resulting in greater                                             travel of the actuator tip.                                             Gears  Gears can be used to increase travel                                                             ♦ Low force, low travel                        at the expense of duration. Circular                                                                actuators can be used                                     gears, rack and pinion, ratchets, and                                                            ♦ Can be fabricated using                      other gearing methods can be used.                                                                  standard surface MEMS                                                          processes                                          Catch  The actuator controls a small catch.                                                             ♦ Very low actuator energy                     The catch either enables or disables                                                             ♦ Very small actuator size                     movement of an ink pusher that is                                              controlled in a bulk manner.                                            Buckle plate                                                                          A buckle plate can be used to change                                                             ♦ Very fast movement                           a slow actuator into a fast motion. It                                                              achievable                                                can also convert a high force, low                                             travel actuator into a high travel,                                            medium force motion.                                                    Tapered                                                                               A tapered magnetic pole can increase                                                             ♦ Linearizes the magnetic               magnetic pole                                                                         travel at the expense of force.                                                                     force/distance curve                               Lever  A lever and fulcrum is used to                                                                   ♦ Matches low travel actuator                  transform a motion with small travel                                                                with higher travel                                        and high force into a motion with                                                                   requirements                                              longer travel and lower force. The                                                               ♦ Fulcrum area has no linear                   lever can also reverse the direction of                                                             movement, and can be used                                 travel.              for a fluid seal                                   Rotary The actuator is connected to a rotary                                                            ♦ High mechanical advantage             impeller                                                                              impeller. A small angular deflection                                                             ♦ The ratio of force to travel                 of the actuator results in a rotation of                                                            of the actuator can be                                    the impeller vanes, which push the                                                                  matched to the nozzle                                     ink against stationary vanes and out                                                                requirements by varying the                               of the nozzle.       number of impeller vanes                           Acoustic lens                                                                         A refractive or diffractive (e.g: zone                                                           ♦ No moving parts                              plate) acoustic lens is used to                                                concentrate sound waves.                                                Sharp  A sharp point is used to concentrate                                                             ♦ Simple construction                   conductive                                                                            an electrostatic field.                                                 point                                                                          __________________________________________________________________________     Actuator                                                                       amplification                                                                         Disadvantages     Examples                                              __________________________________________________________________________     None   ♦ Many actuator mechanisms have                                                    ♦ Thermal Bubble                                  insufficient travel, or insufficient force,                                                      Inkjet                                                       to efficiently drive the drop ejection                                                        ♦ IJ01, IJ02, IJ06, IJ07                          process        ♦ IJ16, IJ25, IJ26                      Differential                                                                          ♦ High stresses are involved                                                       ♦ Piezoelectric                         expansion                                                                             ♦ Care must be taken that the materaisl                                            ♦ IJ03, IJ09, IJ17-IJ24                 bend actuator                                                                            do not delaminate                                                                             ♦ IJ27, IJ29-IJ39, IJ42,                       ♦ Residual bend resulting from high                                                ♦ IJ43, IJ44                                      temperature or high stress during                                              formation                                                            Transient bend                                                                        ♦ High stresses are involved                                                       ♦ IJ40, IJ41                            actuator                                                                              ♦ Care must be taken that the materials                             do not delaminate                                                    Actuator stack                                                                        ♦ Increased fabrication complexity                                                 ♦ Some piezoelectric                           ♦ Increased possiblity of short circuits                                              ink jets                                                     due to pinholes                                                                               ♦ IJ04                                  Multiple                                                                              ♦ Actuator forces may not add linearly,                                            ♦ IJ12, IJ13, IJ18, IJ20                acutators                                                                                reducing efficiency                                                                           ♦ IJ22, IJ28, IJ42, IJ43                Linear Spring                                                                         ♦ Requires print head area for the                                                 ♦ IJ15                                  Reverse spring                                                                        ♦ Fabrication complexity                                                           ♦ IJ05, IJ11                                   ♦ High stress in the spring                               Coiled ♦ Generally restricted to planar                                                   ♦ IJ17, IJ21, IJ34, IJ35                actuator                                                                                 implementations due to extreme                                                 fabrication difficulty in other                                                orientations.                                                        Flexure bend                                                                          ♦ Care must be taken not to exceed                                                 ♦ IJ10, IJ19, IJ33                      actuator                                                                                 elastic limit in the flexure area                                           ♦ Stress distribution is very uneven                             ♦ Difficult to accurately model with                                finite element analysis                                              Gears  ♦ Moving parts are required                                                        ♦ IJ13                                         ♦ Several actuator cycles are required                           ♦ More complex drive electronics                                 ♦ Complex construction                                           ♦ Friction, friction, and wear are possible               Catch  ♦ Complex construction                                                             ♦ IJ10                                         ♦ Requires external force                                        ♦ Unsuitable for pigmented inks                           Buckle plate                                                                          ♦ Must stay within elastic limits of                                               ♦ S. Hirata et al, "An                            materials for long device life                                                                   Ink-jet Head . . . ",                                     ♦ High stresses involved                                                              Proc. IEEE MEMS,                                          ♦ Generally high power requirement                                                    Feb. 1996, pp 418-                                                             423.                                                                        ♦ IJ18, IJ27                            Tapered                                                                               ♦ Complex construction                                                             ♦ IJ14                                  magnetic pole                                                                  Lever  ♦ High stress around the fulcrum                                                   ♦ IJ32, IJ36, IJ37                      Rotary ♦ Complex construction                                                             ♦ IJ28                                  impeller                                                                              ♦ Unsuitable for pigmented inks                           Acoustic lens                                                                         ♦ Large area required                                                              ♦ 1993 Hadimioglu et                           ♦ Only relevant for acoustic ink jets                                                 al, EUP 550, 192                                                            ♦ 1993 Elrod et al, EUP                                             572,220                                            Sharp  ♦ Difficult to fabricate using standard                                            ♦ Tone-Jet                              conductive                                                                               VLSI processes for a surface ejecting                                point     ink-jet                                                                     ♦ Only relevant for electrostatic ink                     __________________________________________________________________________            jets                                                               

    __________________________________________________________________________     ACTUATOR MOTION                                                                __________________________________________________________________________     Actuator                                                                       motion Description       Advantages                                            __________________________________________________________________________     Volume The volume of the actuator changes,                                                              ♦ Simple construction in the            expansion                                                                             pushing the ink in all directions.                                                                  case of thermal ink jet                            Linear, normal                                                                        The actuator moves in a direction                                                                ♦ Efficient coupling to ink             to chip surface                                                                       normal to the print head surface. The                                                               drops ejected normal to the                               nozzle is typically in the line of                                                                  surface                                                   movement.                                                               Linear, parallel                                                                      The actuator moves parallel to the                                                               ♦ Suitable for planar                   to chip surface                                                                       print head surface. Drop ejection                                                                   fabrication                                               may still be normal to the surface.                                     Membrane                                                                              An actuator with a high force but                                                                ♦ The effective area of the             push   small area is used to push a stiff                                                                  actuator becomes the                                      membrane that is in contact with the                                                                membrane area                                             ink.                                                                    Rotary The actuator causes the rotation of                                                              ♦ Rotary levers may be used                    some element, such a grill or                                                                       to increase travel                                        impeller          ♦ Small chip area                                                  requirements                                        Bend   The actuator bends when energized.                                                               ♦ A very small change in                       This may be due to differential                                                                     dimensions can be                                         thermal expansion, piezoelectric                                                                    converted to a large motion.                              expansion, magnetostriction, or other                                          form of relative dimensional change.                                    Swivel The actuator swivels around a central                                                            ♦ Allows operation where the                   pivot. This motion is suitable where                                                                net linear force on the                                   there are opposite forces applied to                                                                paddle is zero                                            opposite sides of the paddle, e.g.                                                               ♦ Small chip area                              Lorenz force.        requirements                                       Straighten                                                                            The actuator is normally bent, and                                                               ♦ Can be used with shape                       straightens when energized.                                                                         memory alloys where the                                                        austenic phase is planar                           Double bend                                                                           The actuator bends in one direction                                                              ♦ One actuator can be used to                  when one element is energized, and                                                                  power two nozzles.                                        bends the other way when another                                                                 ♦ Reduced chip size.                           element is energized.                                                                            ♦ Not sensitive to ambient                                          temperature                                        Shear  Energizing the actuator causes a                                                                 ♦ Can increase the effective                   shear motion in the actuator material.                                                              travel of piezoelectric                                                        actuators                                          Radial The actuator squeezes an ink                                                                     ♦ Relatively easy to fabricate          constriction                                                                          reservoir, forcing ink from a                                                                       single nozzles from glass                                 constricted nozzle.                                                                                 tubing as macroscopic                                                          structures                                         Coil/uncoil                                                                           A coiled actuator uncoils or coils                                                               ♦ Easy to fabricate as a planar                more tightly. The motion of the free                                                                VLSI process                                              end of the actuator ejects the ink.                                                              ♦ Small area required,                                              therefore low cost                                 Bow    The actuator bows (or buckles) in the                                                            ♦ Can increase the speed of                    middle when energized.                                                                              travel                                                                      ♦ Mechanically rigid                    Push-Pull                                                                             Two actuators control a shutter. One                                                             ♦ The structure is pinned at                   actuator pulls the shutter, and the                                                                 both ends, so has a high                                  other pushes it.     out-of-plane rigidity                              Curl inwards                                                                          A set of actuators curl inwards to                                                               ♦ Good fluid flow to the                       reduce the volume of ink that they                                                                  region behind the actuator                                enclose.             increases efficiency                               Curl outwards                                                                         A set of actuators curl outwards,                                                                ♦ Relatively simple                            pressurizing ink in a chamber                                                                       construction                                              surrounding the actuators, and                                                 expelling ink from a nozzle in the                                             chamber.                                                                Iris   Multiple vanes enclose a volume of                                                               ♦ High efficiency                              ink. These simultaneously rotate,                                                                ♦ Small chip area                              reducing the volume between the                                                vanes.                                                                  Acoustic                                                                              The actuator vibrates at a high                                                                  ♦ The actuator can be                   vibration                                                                             frequency.           physically distant from the                                                    ink                                                None   In various ink jet designs the actuator                                                          ♦ No moving parts                              does not move.                                                          __________________________________________________________________________     Actuator                                                                       motion Disadvantages     Examples                                              __________________________________________________________________________     Volume ♦ High energy is typically required                                                ♦ Hewlett-Packard                       expansion                                                                                achieve volume expansion. This leads                                                             Thermal Inkjet                                               to thermal stress, cavitation, and                                                            ♦ Canon Bubblejet                                 kogation in thermal ink jet                                                    implementations                                                      Linear, normal                                                                        ♦ High fabrication complexity may be                                               ♦ IJ01, IJ02, IJ04, IJ07                to chip surface                                                                          required to achieve perpendicular                                                             ♦ IJ11, IJ14                                      motion                                                               Linear, parallel                                                                      ♦ Fabrication complexity                                                           ♦ IJ12, IJ13, IJ15, IJ33,               to chip surface                                                                       ♦ Friction                                                                         ♦ IJ34, IJ35, IJ36                             ♦ Stiction                                                Membrane                                                                              ♦ Fabrication complexity                                                           ♦ 1982 Howkins U.S. Pat. No.            push   ♦ Actuator size                                                                       4,459,601                                                 ♦ Difficulty of integration in a VLSI                               process                                                              Rotary ♦ Device complexity                                                                ♦ IJ05, IJ08, IJ13, IJ28                       ♦ May have friction at a pivot point                      Bend   ♦ Requires the actuator to be made                                                 ♦ 1970 Kyser et al                                at least two distinct layers, or to have a                                                       U.S. Pat. No. 3,946,398                                      thermal difference across the actuator                                                        ♦ 1973 Stemme U.S. Pat. No.                                         3,747,120                                                                   ♦ IJ03, IJ09, IJ10, IJ19                                         ♦ IJ23, IJ24, IJ25, IJ29                                         ♦ IJ30, IJ31, IJ33, IJ34                                         ♦ IJ35                                  Swivel ♦ Inefficient coupling to the ink motion                                           ♦ IJ06                                  Straighten                                                                            ♦ Requires careful balance of stresses                                             ♦ IJ26, IJ32                                      ensure that the quiescent bend is                                              accurate                                                             Double bend                                                                           ♦ Difficult to make the drops ejected                                              ♦ IJ36, IJ37, IJ38                                both bend directions identical.                                             ♦ A small efficiency loss compared to                               equivalent single bend actuators.                                    Shear  ♦ Not readily applicable to other actuator                                         ♦ 1985 Fishbeck U.S. Pat. No.                     mechanisms        4,584,590                                          Radial ♦ High force required                                                              ♦ 1970 Zoltan U.S. Pat. No.             constriction                                                                          ♦ Inefficient                                                                         3,683,212                                                 ♦ Difficult to integrate with VLSI                                  processes                                                            Coil/uncoil                                                                           ♦ Difficult to fabricate for non-planar                                            ♦ IJ17, IJ21, IJ34, IJ35                          devices                                                                     ♦ Poor out-of-plane stiffness                             Bow    ♦ Maximum travel is constrained                                                    ♦ IJ16, IJ18, IJ27                             ♦ High force required                                     Push-Pull                                                                             ♦ Not readily suitable for inkjets                                                 ♦ IJ18                                            directly push the ink                                                Curl inwards                                                                          ♦ Design complexity                                                                ♦ IJ20, IJ42                            Curl outwards                                                                         ♦ Relatively large chip area                                                       ♦ IJ43                                  Iris   ♦ High fabrication complexity                                                      ♦ IJ22                                         ♦ Not suitable for pigmented inks                         Acoustic                                                                              ♦ Large area required for efficient                                                ♦ 1993 Hadimioglu et                    vibration                                                                                operation at useful frequencies                                                                  al, EUP 550,192                                           ♦ Acoustic coupling and crosstalk                                                  ♦ 1993 Elrod et al, EUP                        ♦ Complex drive circuitry                                                             572,220                                                   ♦ Poor control of drop volume and                                   position                                                             None   ♦ Various other tradeoffs are required                                             ♦ Silverbrook, EP 0771                            eliminate moving parts                                                                           658 A2 and related                                                             patent applications                                                         ♦ Tone-jet                              __________________________________________________________________________

    __________________________________________________________________________     NOZZLE REFILL METHOD                                                           __________________________________________________________________________     Nozzle refill                                                                  method Description       Advantages                                            __________________________________________________________________________     Surface                                                                               After the actuator is energized, it                                                              ♦ Fabrication simplicity                tension                                                                               typically returns rapidly to its normal                                                          ♦ Operational simplicity                       position. This rapid return sucks in                                           air through the nozzle opening. The                                            ink surface tension at the nozzle then                                         exerts a small force restoring the                                             meniscus to a minimum area.                                             Shuttered                                                                             Ink to the nozzle chamber is                                                                     ♦ High speed                            oscillating ink                                                                       provided at a pressure that oscillates                                                           ♦ Low actuator energy, as the           pressure                                                                              at twice the drop ejection frequency.                                                               actuator need only open or                                When a drop is to be ejected, the                                                                   close the shutter, instead of                             shutter is opened for 3 half cycles:                                                                ejecting the ink drop                                     drop ejection, actuator return, and                                            refill.                                                                 Refill actuator                                                                       After the main actuator has ejected a                                                            ♦ High speed, as the nozzle is                 drop a second (refill) actuator is                                                                  actively refilled                                         energized. The refill actuator pushes                                          ink into the nozzle chamber. The                                               refill actuator returns slowly, to                                             prevent its return from emptying the                                           chamber again.                                                          Positive ink                                                                          The ink is held a slight positive                                                                ♦ High refill rate, therefore a         pressure                                                                              pressure. After the ink drop is                                                                     high drop repetition rate is                              ejected, the nozzle chamber fills                                                                   possible                                                  quickly as surface tension and ink                                             pressure both operate to refill the                                            nozzle.                                                                 __________________________________________________________________________     Nozzle refill                                                                  method Disadvantages     Examples                                              __________________________________________________________________________     Surface                                                                               ♦ Low speed                                                                        ♦ Thermal inkjet                        tension                                                                               ♦ Surface tension force relatively                                                 ♦ Piezoelectric inkjet                            compared to actuator force                                                                    ♦ IJ01-IJ07, IJ10-IJ14                         ♦ Long refill time usually dominates                                               ♦ IJ16, IJ20, IJ22-IJ45                           total repetition rate                                                Shuttered                                                                             ♦ Requires common ink pressure                                                     ♦ IJ08, IJ13, IJ15, IJ17                oscillating ink                                                                          oscillator     ♦ IJ18, IJ19, IJ21                      pressure                                                                              ♦ May not be suitable for pigmented inks                  Refill actuator                                                                       ♦ Requires two independent actuators                                               ♦ IJ09                                            nozzle                                                               Positive Ink                                                                          ♦ Surface spill must be prevented                                                  ♦ Silverbrook, EP 0771                  pressure                                                                              ♦ Highly hydrophobic print head                                                       658 A2 and related                                           surfaces are required                                                                            patent applications                                                         ♦ Alternative for:                                               ♦ IJ01-IJ07, IJ10-IJ14                                           ♦ IJ16, IJ20, IJ22-IJ45                 __________________________________________________________________________

    __________________________________________________________________________     METHOD OF RESTRICTING BACK-FLOW THROUGH INLET                                  __________________________________________________________________________     Inlet back-flow                                                                restriction                                                                    method Description       Advantages                                            __________________________________________________________________________     Long inlet                                                                            The ink inlet channel to the nozzle                                                              ♦ Design simplicity                     channel                                                                               chamber is made long and relatively                                                              ♦ Operational simplicity                       narrow, relying on viscous drag to                                                               ♦ Reduces crosstalk                            reduce inlet back-flow.                                                 Positive ink                                                                          The ink is under a positive pressure,                                                            ♦ Drop selection and                    pressure                                                                              so that in the quiescent state some of                                                              separation forces can be                                  the ink drop already protrudes from                                                                 reduced                                                   the nozzle.       ♦ Fast refill time                             This reduces the pressure in the                                               nozzle chamber which is required to                                            eject a certain volume of ink. The                                             reduction in chamber pressure results                                          in a reduction in ink pushed out                                               through the inlet.                                                      Baffle One or more baffles are placed in the                                                            ♦ The refill rate is not as                    inlet ink flow. When the actuator is                                                                restricted as the long inlet                              energized, the rapid ink movement                                                                   method.                                                   creates eddies which restrict the flow                                                           ♦ Reduces crosstalk                            through the inlet. The slower refill                                           process is unrestricted, and does not                                          result in eddies.                                                       Flexible flap                                                                         In this method recently disclosed by                                                             ♦ Significantly reduces back-           restricts inlet                                                                       Canon, the expanding actuator                                                                       flow for edge-shooter                                     (bubble) pushes on a flexible flap                                                                  thermal ink jet devices                                   that restricts the inlet.                                               Inlet filter                                                                          A filter is located between the ink                                                              ♦ Additional advantage of ink                  inlet and the nozzle chamber. The                                                                   filtration                                                filter has a multitude of small holes                                                            ♦ Ink filter may be fabricated                 or slots, restricting ink flow. The                                                                 with no additional process                                filter also removes particles which                                                                 steps                                                     may block the nozzle.                                                   Small inlet                                                                           The ink inlet channel to the nozzle                                                              ♦ Design simplicity                     compared to                                                                           chamber has a substantially smaller                                     nozzle cross section than that of the nozzle,                                         resulting in easier ink egress out of                                          the nozzle than out of the inlet.                                       Inlet shutter                                                                         A secondary actuator controls the                                                                ♦ Increases speed of the ink-                  position of a shutter, closing off the                                                              jet print head operation                                  ink inlet when the main actuator is                                            energized.                                                              The inlet is                                                                          The method avoids the problem of                                                                 ♦ Back-flow problem is                  located behind                                                                        inlet back-flow by arranging the ink-                                                               eliminated                                         the ink-                                                                              pushing surface of the actuator                                         pushing                                                                               between the-inlet and the nozzle.                                       surface                                                                        Part of the                                                                           The actuator and a wall of the ink                                                               ♦ Significant reductions in             actuator                                                                              chamber are arranged so that the                                                                    back-flow can be achieved                          moves to shut                                                                         motion of the actuator closes off the                                                            ♦ Compact designs possible              off the inlet                                                                         inlet.                                                                  Nozzle In some configurations of ink jet,                                                               ♦ Ink back-flow problem is              actuator does                                                                         there is no expansion or movement                                                                   eliminated                                         not result in                                                                         of an actuator which may cause ink                                      ink back-flow                                                                         back-flow through the inlet.                                            __________________________________________________________________________     Inlet back-flow                                                                restriction                                                                    method Disadvantages     Examples                                              __________________________________________________________________________     Long inlet                                                                            ♦ Restricts refill rate                                                            ♦ Thermal inkjet                        channel                                                                               ♦ May result in a relatively large                                                 ♦ Piezoelectric inkjet                            area           ♦ IJ42, IJ43                                   ♦ Only partially effective                                Positive ink                                                                          ♦ Requires a method (such as a nozzle                                              ♦ Silverbrook, EP 0771                  pressure                                                                                 rim or effective hydrophobizing, or                                                              658 A2 and related                                           both) to prevent flooding of the                                                                 patent applications                                          ejection surface of the print head.                                                           ♦ Possible operation of                                             the following:                                                              ♦ IJ01-IJ07, IJ09-IJ12                                           ♦ IJ14, IJ16, IJ20, IJ22,                                        ♦ IJ23-IJ34, IJ36-IJ41                                           ♦ IJ44                                  Baffle ♦ Design complexity                                                                ♦ HP Thermal Ink Jet                           ♦ May increase fabrication complexity                                              ♦ Tektronix                                       (e.g. Tetronix hot melt Piezoelectric                                                            piezoelectric ink jet                                        print heads).                                                        Flexible flap                                                                         ♦ Not applicable to most inkjet                                                    ♦ Canon                                 restricts inlet                                                                          configurations                                                              ♦ Increased fabrication complexity                               ♦ Inelastic deformation of polymide flap                            results in creep over extended use                                   Inlet filter                                                                          ♦ Restricts refill rate                                                            ♦ IJ04, IJ12, IJ24, IJ27                       ♦ May result in complex construction                                               ♦ IJ29, IJ30                            Small inlet                                                                           ♦ Restricts refill rate                                                            ♦ IJ02, IJ37, IJ44                      compared to                                                                           ♦ May result in a relatively large chip                   nozzle    area                                                                        ♦ Only partially effective                                Inlet shutter                                                                         ♦ Requires separate refill actuator                                                ♦ IJ09                                            drive circuit                                                        The inlet is                                                                          ♦ Requires careful design to minimize                                              ♦ IJ01, IJ03, IJ05, IJ06                located behind                                                                           the negative pressure behing the paddle                                                       ♦ IJ07, IJ10, IJ11, IJ14                the ink-                 ♦ IJ16, IJ22, IJ23, IJ25                pushing                  ♦ IJ28, IJ31, IJ32, IJ33                surface                  ♦ IJ34, IJ35, IJ36, IJ39                                         ♦ IJ40, IJ41                            Part of the                                                                           ♦ Small increase in fabrication                                                    ♦ IJ07, IJ20, IJ26, IJ38                actuator                                                                                 complexity                                                           moves to shut                                                                  off the inlet                                                                  Nozzle ♦ None related to ink back-flow on                                                 ♦ Silverbrook, EP 0771                  actuator does                                                                            actuation         658 A2 and related                                 not result in               patent aplications                                 ink back-flow            ♦ Valve-jet                                                      ♦ Tone-jet                                                       ♦ IJ08, IJ13, IJ15, IJ17                                         ♦ IJ18, IJ19, IJ21                      __________________________________________________________________________

    __________________________________________________________________________     NOZZLE CLEARING METHOD                                                         __________________________________________________________________________     Nozzle                                                                         Clearing                                                                       method Description       Advantages                                            __________________________________________________________________________     Normal nozzle                                                                         All of the nozzles are fired                                                                     ♦ No added complexity on the            firing periodically, before the ink has a                                                                  print head                                                chance to dry. When not in use the                                             nozzles are sealed (capped) against                                            air.                                                                           The nozzle firing is usually                                                   performed during a special clearing                                            cycle, after first moving the print                                            head to a cleaning station.                                             Extra power to                                                                        In systems which heat the ink, but do                                                            ♦ Can be highly effective if            ink heater                                                                            not boil it under normal situations,                                                                the heater is adjacent to the                             nozzle clearing can be achieved by                                                                  nozzle                                                    over-powering the heater and boiling                                           ink at the nozzle.                                                      Rapid  The actuator is fired in rapid                                                                   ♦ Does not require extra drive          succession of                                                                         succession. In some configurations,                                                                 circuits on the print head                         actuator                                                                              this may cause heat build-up at the                                                              ♦ Can be readily controlled             pulses nozzle which boils the ink, clearing                                                                and initiated by digital logic                            the nozzle. In other situations, it may                                        cause sufficient vibrations to                                                 dislodge clogged nozzles.                                               Extra power to                                                                        Where an actuator is not normally                                                                ♦ A simple solution where               ink pushing                                                                           driven to the limit of its motion,                                                                  applicable                                         actuator                                                                              nozzle clearing may be assisted by                                             providing an enhanced drive signal                                             to the actuator.                                                        Acoustic                                                                              An ultrasonic wave is applied to the                                                             ♦ A high nozzle clearing                resonance                                                                             ink chamber. This wave is of an                                                                     capability can be achieved                                appropriate amplitude and frequency                                                              ♦ May be implemented at                        to cause sufficient force at the nozzle                                                             very low cost in systems                                  to clear blockages. This is easiest to                                                              which already include                                     achieve if the ultrasonic wave is at a                                                              acoustic actuators                                        resonant frequency of the ink cavity.                                   Nozzle A microfabricated plate is pushed                                                                ♦ Can clear severely clogged            clearing plate                                                                        against the nozzles. The plate has a                                                                nozzles                                                   post for every nozzle. The array of                                            posts                                                                   Ink pressure                                                                          The pressure of the ink is                                                                       ♦ May be effective where                pulse  temporarily increased so that ink                                                                   other methods cannot be                                   streams from all of the nozzles. This                                                               used                                                      may be used in conjunction with                                                actuator energizing.                                                    Print head                                                                            A flexible `blade` is wiped across the                                                           ♦ Effective for planar print            wiper  print head surface. The blade is                                                                    head surfaces                                             usually fabricated from a flexible                                                               ♦ Low cost                                     polymer, e.g. rubber or synthetic                                              elastomer.                                                              Separate ink                                                                          A separate heater is provided at the                                                             ♦ Can be effective where                boiling heater                                                                        nozzle although the normal drop e-                                                                  other nozzle clearing                                     ection mechanism does not require it.                                                               methods cannot be used                                    The heaters do not require individual                                                            ♦ Can be implemented at no                     drive circuits, as many nozzles can                                                                 additional cost in some                                   be cleared simultaneously, and no                                                                   inkjet configurations                                     imaging is required.                                                    __________________________________________________________________________     Nozzle                                                                         Clearing                                                                       method Disadvantages     Examples                                              __________________________________________________________________________     Normal nozzle                                                                         ♦ May not be sufficient to displace                                                ♦ Most ink jet systems                  firing    ink            ♦ IJ01-IJ07, IJ09-IJ12                                           ♦ IJ14, IJ16, IJ20, IJ22                                         ♦ IJ23-IJ34, IJ36-IJ45                  Extra power to                                                                        ♦ Requires higher drive voltage for                                                ♦ Silverbrook, EP 0771                  ink heater                                                                               clearing          658 A2 and related                                        ♦ May require larger drive transistors                                                patent applications                                Rapid  ♦ Effectiveness depends substantially                                              ♦ May be used with:                     succession of                                                                            upon the configuration of the inkjet                                                          ♦ IJ01-IJ07, IJ09-IJ11                  actuator                                                                                 nozzle         ♦ IJ14, IJ16, IJ20, IJ22                pulses                   ♦ IJ23-IJ25, IJ27-IJ34                                           ♦ IJ36-IJ45                             Extra power to                                                                        ♦ Not suitable where there is a hard                                               ♦ May be used with:                     ink pushing                                                                              to actuator movement                                                                          ♦ IJ03, IJ09, IJ16, IJ20                actuator                 ♦ IJ23, IJ24, IJ25, IJ27                                         ♦ IJ29, IJ30, IJ31, IJ32                                         ♦ IJ39, IJ40, IJ41, IJ42                                         ♦ IJ43, IJ44, IJ45                      Acoustic                                                                              ♦ High implementation cost if system                                               ♦ IJ08, IJ13, IJ15, IJ17                resonance                                                                                does not already include an acoustic                                                          ♦ IJ18, IJ19, IJ21                                actuator                                                             Nozzle ♦ Accurate mechanical alignment is                                                 ♦ Silverbrook, EP 0771                  clearing plate                                                                           required          658 A2 and related                                        ♦ Moving parts are required                                                           patent applications                                       ♦ There is risk of damage to the nozzles                         ♦ Accurate fabrication is required                        Ink pressure                                                                          ♦ Requires pressure pump or other                                                  ♦ May be used with all                  pulse     pressure actuator                                                                                IJ series ink jets                                        ♦ Expensive                                                      ♦ Wasteful of ink                                         Print head                                                                            ♦ Difficult to use if print head surface                                           ♦ Many ink jet systems                  wiper     non-planar or very fragile                                                  ♦ Requires mechanical parts                                      ♦ Blade can wear out in high volume                                 print systems                                                        Separate ink                                                                          ♦ Fabrication complexity                                                           ♦ Can be used with                      boiling heater              many IJ series ink                                                             jets                                               __________________________________________________________________________

    __________________________________________________________________________     NOZZLE PLATE CONSTRUCTION                                                      __________________________________________________________________________     Nozzle plate                                                                   construction                                                                          Description       Advantages                                            __________________________________________________________________________     Electroformed                                                                         A nozzle plate is separately                                                                     ♦ Fabrication simplicity                nickel fabricated from electroformed nickel,                                          and bonded to the print head chip.                                      Laser ablated                                                                         Individual nozzle holes are ablated                                                              ♦ No masks required                     or drilled                                                                            by an intense UV laser in a nozzle                                                               ♦ Can be quite fast                     polymer                                                                               plate, which is typically a polymer                                                              ♦ Some control over nozzle                     such as polyimide or polysulphone                                                                   profile is possible                                                         ♦ Equipment required is                                             relatively low cost                                Silicon micro-                                                                        A separate nozzle plate is                                                                       ♦ High accuracy is attainable           machined                                                                              micromachined from single crystal                                              silicon, and bonded to the print head                                          wafer.                                                                  Glass  Fine glass capillaries are drawn from                                                            ♦ No expensive equipment                capillaries                                                                           glass tubing. This method has been                                                                  required                                                  used for making individual nozzles,                                                              ♦ Simple to make single                        but is difficult to use for bulk                                                                    nozzles                                                   manufacturing of print heads with                                              thousands of nozzles.                                                   Monolithic,                                                                           The nozzle plate is deposited as a                                                               ♦ High accuracy (<1 μm)              surface micro-                                                                        layer using standard VLSI deposition                                                             ♦ Monolithic                            machined                                                                              techniques. Nozzles are etched in the                                                            ♦ Low cost                              using VLSI                                                                            nozzle plate using VLSI lithography                                                              ♦ Existing processes can be             lithographic                                                                          and etching.         used                                               processes                                                                      Monolithic,                                                                           The nozzle plate is a buried etch stop                                                           ♦ High accuracy (<1 μm)              etched in the wafer. Nozzle chambers are                                                                ♦ Monolithic                            through                                                                               etched in the front of the wafer, and                                                            ♦ Low cost                              substrate                                                                             the wafer is thinned from the back                                                               ♦ No differential expansion                    side. Nozzles are then etched in the                                           etch stop layer.                                                        No nozzle                                                                             Various methods have been tried to                                                               ♦ No nozzles to become                  plate  eliminate the nozzles entirely, to                                                                  clogged                                                   prevent nozzle clogging. These                                                 include thermal bubble mechanisms                                              and acoustic lens mechanisms                                            Trough Each drop ejector has a trough                                                                   ♦ Reduced manufacturing                        through which a paddle moves.                                                                       complexity                                                There is no nozzle plate.                                                                        ♦ Monolithic                            Nozzle slit                                                                           The elimination of nozzle holes and                                                              ♦ No nozzles to become                  instead of                                                                            replacement by a slit encompassing                                                                  clogged                                            individual                                                                            many actuator positions reduces                                         nozzles                                                                               nozzle clogging, but increases                                                 crosstalk due to ink surface waves                                      __________________________________________________________________________     Nozzle plate                                                                   construction                                                                          Disadvantages     Examples                                              __________________________________________________________________________     Electroformed                                                                         ♦ High temperatures and pressures are                                              ♦ Hewlett Packard                       nickel    required to bond nozzle plate                                                                    Thermal Inkjet                                            ♦ Minimum thickness constraints                                  ♦ Differential thermal expansion                          Laser ablated                                                                         ♦ Each hole must be individually formed                                            ♦ Canon Bubblejet                       or drilled                                                                            ♦ Special equipment required                                                       ♦ 1988 Sercel et al.,                   polymer                                                                               ♦ Slow where there are many thousands                                                 SPIE, Vol. 998                                               of nozzles per print head                                                                        Excimer Beam                                              ♦ May produce thin burrs at exit holes                                                Applications, pp. 76-83                                                     ♦ 1993 Watanabe et al.,                                             U.S. Pat. No. 5,208,604                            Silicon micro-                                                                        ♦ Two part construction                                                            ♦ K. Bean, IEEE                         machined                                                                              ♦ High cost                                                                           Transactions on                                           ♦ Requires precision alignment                                                        Electron Devices,                                         ♦ Nozzles may be clogged by adhesive                                                  Vol. ED-25, No. 10,                                                            1978, pp 1185-1195                                                          ♦ Xerox 1990 Hawkins                                                et al., U.S. Pat. No.                                                          4,899,187                                          Glass  ♦ Very small nozzle sizes are difficult                                            ♦ 1970 Zoltan U.S. Pat. No.             capillaries                                                                              form              3,683,212                                                 ♦ Not suited for mass production                          Monolithic,                                                                           ♦ Requires sacrificial layer under                                                 ♦ Silverbrook, EP 0771                  surface micro-                                                                           nozzle plate to form the nozzle                                                                  658 A2 and related                                 machined                                                                                 chamber           patent applications                                using VLSI                                                                            ♦ Surface may be fragile to the touch                                              ♦ IJ01, IJ02, IJ04, IJ11                lithographic             ♦ IJ12, IJ17, IJ18, IJ20                processes                ♦ IJ22, IJ24, IJ27, IJ28                                         ♦ IJ29, IJ30, IJ31, IJ32                                         ♦ IJ33, IJ34, IJ36, IJ37                                         ♦ IJ38, IJ39, IJ40, IJ41                                         ♦ IJ42, IJ43, IJ44                      Monolithic,                                                                           ♦ Requires long etch times                                                         ♦ IJ03, IJ05, IJ06, IJ07                etched ♦ Requires a support wafer                                                         ♦ IJ08, IJ09, IJ10, IJ13                through                  ♦ IJ14, IJ15, IJ16, IJ19                substrate                ♦ IJ21, IJ23, IJ25, IJ26                No nozzle                                                                             ♦ Difficult to control drop position                                               ♦ Ricoh 1995 Sekiya et                  plate     accurately        al U.S. Pat. No. 5,412,413                                ♦ Crosstalk problems                                                               ♦ 1993 Hadimioglu et                                                al EUP 550,192                                                              ♦ 1993 Elrod et al EUP                                              572,220                                            Trough ♦ Drop firing direction is sensitive                                               ♦ IJ35                                            wicking.                                                             Nozzle slit                                                                           ♦ Difficult to control drop position                                               ♦ 1989 Saito et al                      instead of                                                                               accurately        U.S. Pat. No. 4,799,068                            individual                                                                            ♦ Crosstalk problems                                      nozzles                                                                        __________________________________________________________________________

    __________________________________________________________________________     DROP EJECTION DIRECTION                                                        __________________________________________________________________________     Ejection                                                                       direction                                                                             Description       Advantages                                            __________________________________________________________________________     Edge   Ink flow is along the surface of the                                                             ♦ Simple construction                   (`edge chip, and ink drops are ejected from                                                             ♦ No silicon etching required           shooter`)                                                                             the chip edge.    ♦ Good heat sinking via                                             substrate                                                                   ♦ Mechanically strong                                            ♦ Ease of chip handing                  Surface                                                                               Ink flow is along the surface of the                                                             ♦ No bulk silicon etching               (`roof shooter`)                                                                      chip, and ink drops are ejected from                                                                required                                                  the chip surface, normal to the plane                                                            ♦ Silicon can make an                          of the chip.         effective heat sink                                                         ♦ Mechanical strength                   Through chip,                                                                         Ink flow is through the chip, and ink                                                            ♦ High ink flow                         forward                                                                               drops are ejected from the front                                                                 ♦ Suitable for pagewidth print          (`up shooter`)                                                                        surface of the chip.                                                                             ♦ High nozzle packing                                               density therefore low                                                          manufacturing cost                                 Through chip,                                                                         Ink flow is through the chip, and ink                                                            ♦ High ink flow                         reverse                                                                               drops are ejected from the rear                                                                  ♦ Suitable for pagewidth print          (`down surface of the chip.                                                                             ♦ High nozzle packing                   shooter`)                   density therefore low                                                          manufacturing cost                                 Through                                                                               Ink flow is through the actuator,                                                                ♦ Suitable for piezoelectric            actuator                                                                              which is not fabricated as part of the                                                              print heads                                               same substrate as the drive                                                    transistors.                                                            __________________________________________________________________________     Ejection                                                                       direction                                                                             Disadvantages     Examples                                              __________________________________________________________________________     Edge   ♦ Nozzles limited to edge                                                          ♦ Canon Bubblejet                       (`edge ♦ High resolution is difficult                                                        1979 Endo et al GB                                 shooter`)                                                                             ♦ Fast color printing requires one                                                    patent 2,007,162                                             head per color ♦ Xerox heater-in-pit                                               1990 Hawkins et al                                                             U.S. Pat. No. 4,899,181                                                     ♦ Tone-jet                              Surface                                                                               ♦ Maximum ink flow is severely                                                     ♦ Hewlett-Packard TIJ                   (`roof shooter`)                                                                         restricted        1982 Vaught et al                                                              U.S. Pat. No. 4,490,728                                                     ♦ IJ02, IJ11, IJ12, IJ20                                         ♦ IJ22                                  Through chip,                                                                         ♦ Requires bulk silicon etching                                                    ♦ Silverbrook, EP 0771                  forward                     658 A2 and related                                 (`up shooter`)              patent applications                                                         ♦ IJ04, IJ17, IJ18, IJ24                                         ♦ IJ27-IJ45                             Through chip,                                                                         ♦ Requires wafer thinning                                                          ♦ IJ01, IJ03, IJ05, IJ06                reverse                                                                               ♦ Requires special handling during                                                 ♦ IJ07, IJ08, IJ09, IJ10                (`down    manufacture    ♦ IJ13, IJ14, IJ15, IJ16                shooter`)                ♦ IJ19, IJ21, IJ23, IJ25                                         ♦ IJ26                                  Through                                                                               ♦ Pagewidth print heads require several                                            ♦ Epson Stylus                          actuator                                                                                 thousand connections to drive circuits                                                        ♦ Tektronix hot melt                           ♦ Cannot be manufactured in standard                                                  piezoelectric ink jets                                    ♦ Cannot be manufactured in standard                                CMOS fabs                                                                   ♦ Complex assembly required                               __________________________________________________________________________

    __________________________________________________________________________     INK TYPE                                                                       __________________________________________________________________________     Ink type                                                                              Description       Advantages                                            __________________________________________________________________________     Aqueous, dye                                                                          Water based ink which typically                                                                  ♦ Environmentally friendly                     contains: water, dye, surfactant,                                                                ♦ No odor                                      humectant, and biocide.                                                        Modern ink dyes have high water-                                               fastness, light fastness                                                Aqueous,                                                                              Water based ink which typically                                                                  ♦ Environmentally friendly              pigment                                                                               contains: water, pigment, surfactant;                                                            ♦ No odor                                      humectant, and biocide.                                                                          ♦ Reduced bleed                                Pigments have an advantage in                                                                    ♦ Reduced wicking                              reduced bleed, wicking and                                                                       ♦ Reduced strikethrough                        strikethrough.                                                          Methyl Ethyl                                                                          MEK is a highly volatile solvent                                                                 ♦ Very fast drying                      Ketone (MEK)                                                                          used for industrial printing on                                                                  ♦ Prints on various substrates                 difficult surfaces such as aluminum                                                                 such as metals and plastics                               cans.                                                                   Alcohol                                                                               Alcohol based inks can be used                                                                   ♦ Fast drying                           (ethanol, 2-                                                                          where the printer must operate at                                                                ♦ Operates at sub-freezing              butanol, and                                                                          temperatures below the freezing                                                                     temperatures                                       others)                                                                               point of water. An example of this is                                                            ♦ Reduced paper cockle                         in-camera consumer photographic                                                                  ♦ Low cost                                     printing.                                                               Phase change                                                                          The ink is solid at room temperature,                                                            ♦ No drying time ink                    (hot melt)                                                                            and is melted in the print head before                                                              instantly freezes on the                                  jetting. Hot melt inks are usually                                                                  print medium                                              wax based, with a melting point                                                                  ♦ Almost any print medium                      around 80° C. After jetting the ink                                                          can be used                                               freezes almost instantly upon                                                                    ♦ No paper cockle occurs                       contacting the print medium or a                                                                 ♦ No wicking occurs                            transfer roller.  ♦ No bleed occurs                                                ♦ No strikethrough occurs               Oil    Oil based inks are extensively used                                                              ♦ High solubility medium for                   in offset printing. They have                                                                       some dyes                                                 advantages in improved                                                                           ♦ Does not cockle paper                        characteristics on paper (especially                                                             ♦ Does not wick through                        no wicking or cockle). Oil soluble                                                                  paper                                                     dies and pigments are required.                                         Microemulsion                                                                         A microemulsion is a stable, self                                                                ♦ Stops ink bleed                              forming emulsion of oil, water, and                                                              ♦ High dye solubility                          surfactant. The characteristic drop                                                              ♦ Water, oil, and amphiphilic                  size is less than 100 nm, and is                                                                    soluble dies, can be used                                 determined by the preferred                                                                      ♦ Can stabilize pigment                        curvature of the surfactant.                                                                        suspensions                                        __________________________________________________________________________     Ink type                                                                              Disadvantages     Examples                                              __________________________________________________________________________     Aqueous, dye                                                                          ♦ Slow drying                                                                      ♦ Most existing inkjets                        ♦ Corrosive                                                                        ♦ All IJ series ink jets                       ♦ Bleeds on paper                                                                  ♦ Silverbrook, EP 0771                         ♦ May strikethrough                                                                   658 A2 and related                                        ♦ Cockles paper                                                                       patent applications                                Aqueous,                                                                              ♦ Slow drying                                                                      ♦ IJ02, IJ04, IJ21, IJ26                pigment                                                                               ♦ Corrosive                                                                        ♦ IJ27, IJ30                                   ♦ Pigment may clog nozzles                                                         ♦ Silverbrook, EP 0771                         ♦ Pigment may clog actuator                                                           658 A2 and related                                           mechanisms        patent applications                                       ♦ Cockles paper                                                                    ♦ Piezoelectric ink-jets                                         ♦ Thermal ink jets                                                  (with significant                                                              restrictions)                                      Methyl Ethyl                                                                          ♦ Odorous                                                                          ♦ All IJ series ink jets                Ketone (MEK)                                                                          ♦ Flammable                                               Alcohol                                                                               ♦ Slight odor                                                                      ♦ All IJ series ink jets                (ethanol, 2-                                                                          ♦ Flammable                                               butanol, and                                                                   others)                                                                        Phase change                                                                          ♦ High viscosity                                                                   ♦ Tektronix hot melt                    (hot melt)                                                                            ♦ Printed ink typically has a `waxy` feel                                             piezoelectric ink jets                                    ♦ Printed pages may `block`                                                        ♦ 1989 Nowak U.S. Pat. No.                     ♦ Ink temperature may be above the                                                    4,820,346                                                    curie point of permanent magnets                                                              ♦ All IJ series ink jets                       ♦ Ink heaters consume power                                      ♦ Long warm-up time                                       Oil    ♦ High viscosity: this is a significant                                            ♦ All IJ series ink jets                          limitation for use in inkjets, which                                           usually require a low viscosity. Some                                          short chain and multi-branched oils                                            have a sufficiently low viscosity.                                          ♦ Slow drying                                             Microemulsion                                                                         ♦ Viscosity higher than water                                                      ♦ All IJ series ink jets                       ♦ Cost is slightly higher than water based                          ink                                                                         ♦ High surfactant concentration required                            (around 5%)                                                          __________________________________________________________________________

Ink Jet Printing

A large number of new forms of ink jet printers have been developed to facilitate alternative ink jet technologies for the image processing and data distribution system. Various combinations of ink jet devices can be included in printer devices incorporated as part of the present invention. Australian Provisional Patent Applications relating to these ink jets which are specifically incorporated by cross reference include:

    ______________________________________                                         Australian                                                                     Provisional                                                                    Number  Filing Date                                                                              Title                                                        ______________________________________                                         PO8066  15-Jul-97 Image Creation Method and Apparatus (IJ01)                   PO8072  15-Jul-97 Image Creation Method and Apparatus (IJ02)                   PO8040  15-Jul-97 Image Creation Method and Apparatus (IJ03)                   PO8071  15-Jul-97 Image Creation Method and Apparatus (IJ04)                   PO8047  15-Jul-97 Image Creation Method and Apparatus (IJ05)                   PO8035  15-Jul-97 Image Creation Method and Apparatus (IJ06)                   PO8044  15-Jul-97 Image Creation Method and Apparatus (IJ07)                   PO8063  15-Jul-97 Image Creation Method and Apparatus (IJ08)                   PO8057  15-Jul-97 Image Creation Method and Apparatus (IJ09)                   PO8056  15-Jul-97 Image Creation Method and Apparatus (IJ10)                   PO8069  15-Jul-97 Image Creation Method and Apparatus (IJ11)                   PO8049  15-Jul-97 Image Creation Method and Apparatus (IJ12)                   PO8036  15-Jul-97 Image Creation Method and Apparatus (IJ13)                   PO8048  15-Jul-97 Image Creation Method and Apparatus (IJ14)                   PO8070  15-Jul-97 Image Creation Method and Apparatus (IJ15)                   PO8067  15-Jul-97 Image Creation Method and Apparatus (IJ16)                   PO8001  15-Jul-97 Image Creation Method and Apparatus (IJ17)                   PO8038  15-Jul-97 Image Creation Method and Apparatus (IJ18)                   PO8033  15-Jul-97 Image Creation Method and Apparatus (IJ19)                   PO8002  15-Jul-97 Image Creation Method and Apparatus (IJ20)                   PO8068  15-Jul-97 Image Creation Method and Apparatus (IJ21)                   PO8062  15-Jul-97 Image Creation Method and Apparatus (IJ22)                   PO8034  15-Jul-97 Image Creation Method and Apparatus (IJ23)                   PO8039  15-Jul-97 Image Creation Method and Apparatus (IJ24)                   PO8041  15-Jul-97 Image Creation Method and Apparatus (IJ25)                   PO8004  15-Jul-97 Image Creation Method and Apparatus (IJ26)                   PO8037  15-Jul-97 Image Creation Method and Apparatus (IJ27)                   PO8043  15-Jul-97 Image Creation Method and Apparatus (IJ28)                   PO8042  15-Jul-97 Image Creation Method and Apparatus (IJ29)                   PO8064  15-Jul-97 Image Creation Method and Apparatus (IJ30)                   PO9389  23-Sep-97 Image Creation Method and Apparatus (IJ31)                   PO9391  23-Sep-97 Image Creation Method and Apparatus (IJ32)                   PP0888  12-Dec-97 Image Creation Method and Apparatus (IJ33)                   PP0891  12-Dec-97 Image Creation Method and Apparatus (IJ34)                   PP0890  12-Dec-97 Image Creation Method and Apparatus (IJ35)                   PP0873  12-Dec-97 Image Creation Method and Apparatus (IJ36)                   PP0993  12-Dec-97 Image Creation Method and Apparatus (IJ37)                   PP0890  12-Dec-97 Image Creation Method and Apparatus (IJ38)                   PP1398  19-Jan-98 An Image Creation Method and Apparatus                                         (IJ39)                                                       PP2592  25-Mar-98 An Image Creation Method and Apparatus                                         (IJ40)                                                       PP2593  25-Mar-98 Image Creation Method and Apparatus (IJ41)                   PP3991  9-Jun-98  Image Creation Method and Apparatus (IJ42)                   PP3987  9-Jun-98  Image Creation Method and Apparatus (IJ43)                   PP3985  9-Jun-98  Image Creation Method and Apparatus (IJ44)                   PP3983  9-Jun-98  Image Creation Method and Apparatus (IJ45)                   ______________________________________                                    

Ink Jet Manufacturing

Further, the present application may utilize advanced semiconductor fabrication techniques in the construction of large arrays of ink jet printers. Suitable manufacturing techniques are described in the following Australian provisional patent specifications incorporated here by cross-reference:

    ______________________________________                                         Australian                                                                     Provisional                                                                    Number   Filing Date                                                                               Title                                                      ______________________________________                                         PO7935   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM01)                                 PO7936   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM02)                                 PO7937   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM03)                                 PO8061   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM04)                                 PO8054   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM05)                                 PO8065   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM06)                                 PO8055   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM07)                                 PO8053   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM08)                                 PO8078   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM09)                                 PO7933   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM10)                                 PO7950   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM11)                                 PO7949   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM12)                                 PO8060   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM13)                                 PO8059   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM14)                                 PO8073   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM15)                                 PO8076   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM16)                                 PO8075   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM17)                                 PO8079   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM18)                                 PO8050   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM19)                                 PO8052   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM20)                                 PO7948   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM21)                                 PO7951   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM22)                                 PO8074   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM23)                                 PO7941   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM24)                                 PO8077   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM25)                                 PO8058   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM26)                                 PO8051   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM27)                                 PO8045   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM28)                                 PO7952   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM29)                                 PO8046   15-Jul-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM30)                                 PO8503   11-Aug-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM30a)                                PO9390   23-Sep-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM31)                                 PO9392   23-Sep-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM32)                                 PP0889   12-Dec-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM35)                                 PP0887   12-Dec-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM36)                                 PP0882   12-Dec-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM37)                                 PP0874   12-Dec-97  A Method of Manufacture of an Image                                            Creation Apparatus (IJM38)                                 PP1396   19-Jan-98  A Method of Manufacture of an Image                                            Creation Apparatus (IJM39)                                 PP2591   25-Mar-98  A Method of Manufacture of an Image                                            Creation Apparatus (IJM41)                                 PP3989   9-Jun-98   A Method of Manufacture of an Image                                            Creation Apparatus (IJM40)                                 PP3990   9-Jun-98   A Method of Manufacture of an Image                                            Creation Apparatus (IJM42)                                 PP3986   9-Jun-98   A Method of Manufacture of an Image                                            Creation Apparatus (IJM43)                                 PP3984   9-Jun-98   A Method of Manufacture of an Image                                            Creation Apparatus (IJM44)                                 PP3982   9-Jun-98   A Method of Manufacture of an Image                                            Creation Apparatus (IJM45)                                 ______________________________________                                    

Fluid Supply

Further, the present application may utilize an ink delivery system to the ink jet head. Delivery systems relating to the supply of ink to a series of ink jet nozzles are described in the following Australian provisional patent specifications, the disclosure of which are hereby incorporated by cross-reference:

    ______________________________________                                         Australian                                                                     Provisional                                                                    Number    Filing Date                                                                               Title                                                     ______________________________________                                         PO8003    15-Jul-97  Supply Method and Apparatus (F1)                          PO8005    15-Jul-97  Supply Method and Apparatus (F2)                          PO9404    23-Sep-97  A Device and Method (F3)                                  ______________________________________                                    

MEMS Technology

Further, the present application may utilize advanced semiconductor microelectromechanical techniques in the construction of large arrays of ink jet printers. Suitable microelectromechanical techniques are described in the following Australian provisional patent specifications incorporated here by cross-reference:

    ______________________________________                                         Australian                                                                     Provisional                                                                    Number    Filing Date                                                                               Title                                                     ______________________________________                                         PO7943    15-Jul-97  A device (MEMS01)                                         PO8006    15-Jul-97  A device (MEMS02)                                         PO8007    15-Jul-97  A device (MEMS03)                                         PO8008    15-Jul-97  A device (MEMS04)                                         PO8010    15-Jul-97  A device (MEMS05)                                         PO8011    15-Jul-97  A device (MEMS06)                                         PO7947    15-Jul-97  A device (MEMS07)                                         PO7945    15-Jul-97  A device (MEMS08)                                         PO7944    15-Jul-97  A device (MEMS09)                                         PO7946    15-Jul-97  A device (MEMS10)                                         PO9393    23-Sep-97  A Device and Method (MEMS11)                              PP0875    12-Dec-97  A Device (MEMS12)                                         PP0894    12-Dec-97  A Device and Method (MEMS13)                              ______________________________________                                    

IR Technologies

Further, the present application may include the utilization of a disposable camera system such as those described in the following Australian provisional patent specifications incorporated here by cross-reference:

    ______________________________________                                         Australian                                                                     Provisional                                                                    Number  Filing Date                                                                              Title                                                        ______________________________________                                         PP0895  12-Dec-97 An Image Creation Method and Apparatus                                         (IR01)                                                       PP0870  12-Dec-97 A Device and Method (IR02)                                   PP0869  12-Dec-97 A Device and Method (IR04)                                   PP0887  12-Dec-97 Image Creation Method and Apparatus (IR05)                   PP0885  12-Dec-97 An Image Production System (IR06)                            PP0884  12-Dec-97 Image Creation Method and Apparatus (IR10)                   PP0886  12-Dec-97 Image Creation Method and Apparatus (IR12)                   PP0871  12-Dec-97 A Device and Method (IR13)                                   PP0876  12-Dec-97 An Image Processing Method and Apparatus                                       (IR14)                                                       PP0877  12-Dec-97 A Device and Method (IR16)                                   PP0878  12-Dec-97 A Device and Method (IR17)                                   PP0879  12-Dec-97 A Device and Method (IR18)                                   PP0883  12-Dec-97 A Device and Method (IR19)                                   PP0880  12-Dec-97 A Device and Method (IR20)                                   PP0881  12-Dec-97 A Device and Method (IR21)                                   ______________________________________                                    

DotCard Technologies

Further, the present application may include the utilization of a data distribution system such as that described in the following Australian provisional patent specifications incorporated here by cross-reference:

    ______________________________________                                         Australian                                                                     Provisional                                                                    Number   Filing Date                                                                               Title                                                      ______________________________________                                         PP2370   16-Mar-98  Data Processing Method and Apparatus                                           (Dot01)                                                    PP2371   16-Mar-98  Data Processing Method and Apparatus                                           (Dot02)                                                    ______________________________________                                    

Artcam Technologies

Further, the present application may include the utilization of camera and data processing techniques such as an Artcam type device as described in the following Australian provisional patent specifications incorporated here by cross-reference:

    ______________________________________                                         Australian                                                                     Provisional                                                                    Number  Filing Date                                                                              Title                                                        ______________________________________                                         PO7991  15-Jul-97 Image Processing Method and Apparatus                                          (ART01)                                                      PO8505  11-Aug-97 Image Processing Method and Apparatus                                          (ART01a)                                                     PO7988  15-Jul-97 Image Processing Method and Apparatus                                          (ART02)                                                      PO7993  15-Jul-97 Image Processing Method and Apparatus                                          (ART03)                                                      PO8012  15-Jul-97 Image Processing Method and Apparatus                                          (ART05)                                                      PO8017  15-Jul-97 Image Processing Method and Apparatus                                          (ART06)                                                      PO8014  15-Jul-97 Media Device (ART07)                                         PO8025  15-Jul-97 Image Processing Method and Apparatus                                          (ART08)                                                      PO8032  15-Jul-97 Image Processing Method and Apparatus                                          (ART09)                                                      PO7999  15-Jul-97 Image Processing Method and Apparatus                                          (ART10)                                                      PO7998  15-Jul-97 Image Processing Method and Apparatus                                          (ART11)                                                      PO8031  15-Jul-97 Image Processing Method and Apparatus                                          (ART12)                                                      PO8030  15-Jul-97 Media Device (ART13)                                         PO8498  11-Aug-97 Image Processing Method and Apparatus                                          (ART14)                                                      PO7997  15-Jul-97 Media Device (ART15)                                         PO7979  15-Jul-97 Media Device (ART16)                                         PO8015  15-Jul-97 Media Device (ART17)                                         PO7978  15-Jul-97 Media Device (ART18)                                         PO7982  15-Jul-97 Data Processing Method and Apparatus                                           (ART19)                                                      PO7989  15-Jul-97 Data Processing Method and Apparatus                                           (ART20)                                                      PO8019  15-Jul-97 Media Processing Method and Apparatus                                          (ART21)                                                      PO7980  15-Jul-97 Image Processing Method and Apparatus                                          (ART22)                                                      PO7942  15-Jul-97 Image Processing Method and Apparatus                                          (ART23)                                                      PO8018  15-Jul-97 Image Processing Method and Apparatus                                          (ART24)                                                      PO7938  15-Jul-97 Image Processing Method and Apparatus                                          (ART25)                                                      PO8016  15-Jul-97 Image Processing Method and Apparatus                                          (ART26)                                                      PO8024  15-Jul-97 Image Processing Method and Apparatus                                          (ART27)                                                      PO7940  15-Jul-97 Data Processing Method and Apparatus                                           (ART28)                                                      PO7939  15-Jul-97 Data Processing Method and Apparatus                                           (ART29)                                                      PO8501  11-Aug-97 Image Processing Method and Apparatus                                          (ART30)                                                      PO8500  11-Aug-97 Image Processing Method and Apparatus                                          (ART31)                                                      PO7987  15-Jul-97 Data Processing Method and Apparatus                                           (ART32)                                                      PO8022  15-Jul-97 Image Processing Method and Apparatus                                          (ART33)                                                      PO8497  11-Aug-97 Image Processing Method and Apparatus                                          (ART30)                                                      PO8029  15-Jul-97 Sensor Creation Method and Apparatus                                           (ART36)                                                      PO7985  15-Jul-97 Data Processing Method and Apparatus                                           (ART37)                                                      PO8020  15-Jul-97 Data Processing Method and Apparatus                                           (ART38)                                                      PO8023  15-Jul-97 Data Processing Method and Apparatus                                           (ART39)                                                      PO9395  23-Sep-97 Data Processing Method and Apparatus                                           (ART4)                                                       PO8021  15-Jul-97 Data Processing Method and Apparatus                                           (ART40)                                                      PO8504  11-Aug-97 Image Processing Method and Apparatus                                          (ART42)                                                      PO8000  15-Jul-97 Data Processing Method and Apparatus                                           (ART43)                                                      PO7977  15-Jul-97 Data Processing Method and Apparatus                                           (ART44)                                                      PO7934  15-Jul-97 Data Processing Method and Apparatus                                           (ART45)                                                      PO7990  15-Jul-97 Data Processing Method and Apparatus                                           (ART46)                                                      PO8499  11-Aug-97 Image Processing Method and Apparatus                                          (ART47)                                                      PO8502  11-Aug-97 Image Processing Method and Apparatus                                          (ART48)                                                      PO7981  15-Jul-97 Data Processing Method and Apparatus                                           (ART50)                                                      PO7986  15-Jul-97 Data Processing Method and Apparatus                                           (ART51)                                                      PO7983  15-Jul-97 Data Processing Method and Apparatus                                           (ART52)                                                      PO8026  15-Jul-97 Image Processing Method and Apparatus                                          (ART53)                                                      PO8027  15-Jul-97 Image Processing Method and Apparatus                                          (ART54)                                                      PO8028  15-Jul-97 Image Processing Method and Apparatus                                          (ART56)                                                      PO9394  23-Sep-97 Image Processing Method and Apparatus                                          (ART57)                                                      PO9396  23-Sep-97 Data Processing Method and Apparatus                                           (ART58)                                                      PO9397  23-Sep-97 Data Processing Method and Apparatus                                           (ART59)                                                      PO9398  23-Sep-97 Data Processing Method and Apparatus                                           (ART60)                                                      PO9399  23-Sep-97 Data Processing Method and Apparatus                                           (ART61)                                                      PO9400  23-Sep-97 Data Processing Method and Apparatus                                           (ART62)                                                      PO9401  23-Sep-97 Data Processing Method and Apparatus                                           (ART63)                                                      PO9402  23-Sep-97 Data Processing Method and Apparatus                                           (ART64)                                                      PO9403  23-Sep-97 Data Processing Method and Apparatus                                           (ART65)                                                      PO9405  23-Sep-97 Data Processing Method and Apparatus                                           (ART66)                                                      PP0959  16-Dec-97 A Data Processing Method and Apparatus                                         (ART68)                                                      PP1397  19-Jan-98 A Media Device (ART69)                                       ______________________________________                                     

I claim:
 1. A thermal actuator comprising an elongate member of heat expansible material adapted to be anchored at a proximal end and having a movable distal end, and a plurality of independently heatable resistive elements incorporated in the elongate member located and arranged such that when selected resistive elements are heated by the application of electric current, the distal end is provided with controlled movement in two mutually orthogonal directions due to controlled bending of said elongate member.
 2. A thermal actuator as claimed in claim 1 wherein said elongate member is substantially rectangular in section having an upper and a lower surface, and wherein three said heatable resistive elements are provided extending in an elongate direction along said member, two of said three elements being located side by side adjacent one of said upper and lower surfaces, and the third of said three elements being located adjacent the other of said upper and lower surfaces, laterally aligned with one of said two elements.
 3. A thermal actuator as claimed in claim 2 wherein said three elements are electrically connected to a common return line at their ends closest to the distal end of said member.
 4. A thermal actuator as claimed in claim 3 wherein said common return line extends in an elongate direction alongside said third of said three elements.
 5. A thermal actuator as claimed in claim 1 wherein said resistive elements are formed from a conductive material having a relatively low coefficient of thermal expansion and said elongate member is formed from an actuation material having a relatively high coefficient of thermal expansion, said resistive elements being configured such that upon heating of said resistive elements, said actuation material is able to expand substantially unhindered by said conductive material.
 6. A thermal actuator as claimed in claim 5 wherein said conductive material is configured to undergo a concertinaing action upon expansion and contraction.
 7. A thermal actuator as claimed in claim 6 wherein said conductive material is formed in a serpentine or helical form.
 8. A thermal actuator as claimed in claim 3 or claim 4 wherein said common line comprises a plate like conductive material having a series of a spaced apart slots arranged for allowing the desired degree of bending of said elongate member.
 9. A thermal actuator as claimed in claim 8 wherein said elongate member is formed from an actuation material, formed around said conductive material including in said slots.
 10. A thermal actuator as claimed in claim 5 wherein said actuation material comprises of substantially polytetrafluoroethylene.
 11. A thermal actuator as claimed in claim 1 wherein the distal end of the thermal actuator is surface treated so as to increase its coefficient of friction.
 12. A cilia array of thermal actuators each constructed in accordance with claim
 1. 13. A cilia array as claimed in claim 12 wherein the distal end of each said thermal actuator is driven such that when continuously engaged with a moveable load the load is urged in one direction only.
 14. A cilia array as claimed in claim 12 wherein adjacent thermal actuators are grouped into different groups with each group being driven together in a different phase cycle from adjacent groups.
 15. A cilia array as claimed in claim 14 wherein the number of phases is four. 